PT-2237 - fixed PostgreSQL DB logs collection (Reopen)

[BON4]

What was added:

• To keep changes minimal, the existing test TestIndividualFiles was modified to cover the new case.
  The test was refactored because the previous implementation couldn't handle files with variable names.
  In /pgdata/<cluster_name>/pg_log, logs are named according to the day/week, so filenames are not known at runtime.

• A new function getAllFilesFromDirectory was added to dumper.go.
  Its purpose is the same as the existing getIndividualFiles, but it supports extracting multiple files from a directory. It is useful because pg log filenames can vary, and there can be multiple log files.

• The contributed code is licensed under GPL v2.0
• Contributor Licence Agreement (CLA) is signed
• util/update-modules has been ran
  (/lib has not been changed)
• Documentation updated
• Test suite update

[svetasmirnova]

pgo test fails:

=== RUN   TestCollectorRunner/Operator_pgo/TestIndividualFiles/Resource_pgo
    main_test.go:401: 
        	Error Trace:	/home/sveta/src/percona/percona-toolkit/src/go/pt-k8s-debug-collector/main_test.go:401
        	            				/home/sveta/go/pkg/mod/github.com/stretchr/testify@v1.11.1/suite/suite.go:115
        	Error:      	Received unexpected error:
        	            	exit status 2
        	Test:       	TestCollectorRunner/Operator_pgo/TestIndividualFiles/Resource_pgo
    main_test.go:403: 
        	Error Trace:	/home/sveta/src/percona/percona-toolkit/src/go/pt-k8s-debug-collector/main_test.go:403
        	            				/home/sveta/go/pkg/mod/github.com/stretchr/testify@v1.11.1/suite/suite.go:115
        	Error:      	Preprocessor Check
        	Test:       	TestCollectorRunner/Operator_pgo/TestIndividualFiles/Resource_pgo
        	Messages:   	test pgo_pg_logs_exist
        	            	resource:pgo
        	            	namespace: pgo
        	            	output is not as expected
        	            	Output: 
        	            	Wanted: [.log]
=== RUN   TestCollectorRunner/Operator_pgo/TestIndividualFiles/Resource_auto
    main_test.go:401: 
        	Error Trace:	/home/sveta/src/percona/percona-toolkit/src/go/pt-k8s-debug-collector/main_test.go:401
        	            				/home/sveta/go/pkg/mod/github.com/stretchr/testify@v1.11.1/suite/suite.go:115
        	Error:      	Received unexpected error:
        	            	exit status 2
        	Test:       	TestCollectorRunner/Operator_pgo/TestIndividualFiles/Resource_auto
    main_test.go:403: 
        	Error Trace:	/home/sveta/src/percona/percona-toolkit/src/go/pt-k8s-debug-collector/main_test.go:403
        	            				/home/sveta/go/pkg/mod/github.com/stretchr/testify@v1.11.1/suite/suite.go:115
        	Error:      	Preprocessor Check
        	Test:       	TestCollectorRunner/Operator_pgo/TestIndividualFiles/Resource_auto
        	Messages:   	test pgo_pg_logs_exist
        	            	resource:auto
        	            	namespace: pgo
        	            	output is not as expected
        	            	Output: 
        	            	Wanted: [.log]

Since we will deprecate pgo soon as per EOL note here: https://docs.percona.com/percona-operator-for-postgresql/1.6.0/, you can simply remove this test.

[Copilot]

Pull request overview

This PR fixes PostgreSQL log collection in the Kubernetes debug collector by enabling extraction of all files from a log directory (where filenames vary at runtime), and updates the integration test to validate that at least one PostgreSQL .log file is included in the produced dump archive.

Changes:

• Added support for dumping an entire directory of “individual files” (used for PostgreSQL pg_log) instead of only known, fixed filenames.
• Added pg log directory mappings for PG v1 (“pgo”) and PG v2 (“pgv2”) resources.
• Refactored TestIndividualFiles to run namespace-specific assertions and added checks for PostgreSQL log presence.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/go/pt-k8s-debug-collector/main_test.go	Refactors individual-file tests and adds checks that PG .log files exist in the archive.
src/go/pt-k8s-debug-collector/dumper/resources.go	Registers PostgreSQL log directories (pg_log) for PG v1 and PG v2 dump collection.
src/go/pt-k8s-debug-collector/dumper/kube_utils.go	Introduces streaming tar execution helpers used for directory/file extraction.
src/go/pt-k8s-debug-collector/dumper/individual_files.go	Reworks individual file dumping to support env substitution and directory extraction via tar streaming.
src/go/pt-k8s-debug-collector/dumper/dumper.go	Normalizes CR type handling when matching pods and dumping summaries/files.

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