fix: Log the cached-data evaluation warning only once per client

[kinyoklion]

Summary

When a variation or allFlagsState call arrives before the client has finished initializing and the feature store already holds data, the server client evaluates against that data and logs a warning. The warning is logged on every such call, so a client that is waiting on its data source while serving from a populated store (for example, a persistent store or an initializer snapshot) floods the log at the evaluation rate.

Both warnings are now logged once per client instance. A private boolean per message records that it was logged. The check and the write happen only inside the branch where the store reports initialized, so a normal evaluation does not touch them. JavaScript is single-threaded, so no synchronization is needed. Each message ends with a note that it is logged once.

The sibling messages for an uninitialized store, which return the default value or an empty state, are unchanged.

This package is shared by the Node server SDK and the edge SDKs, so all of them pick up the change.

[github-actions]

@launchdarkly/js-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 26983 bytes
Compressed size limit: 29000
Uncompressed size: 131377 bytes

[github-actions]

@launchdarkly/js-client-sdk size report
This is the brotli compressed size of the ESM build.
Compressed size: 32597 bytes
Compressed size limit: 34000
Uncompressed size: 116806 bytes

[github-actions]

@launchdarkly/js-client-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 25421 bytes
Compressed size limit: 44000
Uncompressed size: 165321 bytes