fix(nginx): Revert "feat(nginx): use slice module"

[ChandonPierre]

This reverts commit 9cd0135.

Seems to cause a problem with some registries; reverting for now

2023-09-26T02:30:22.656467411Z stderr F 2023/09/26 02:30:22 [error] 105#105: *40145 unexpected status code 401 in slice response while reading response header from upstream, client: 127.0.0.1, server: proxy_caching_, request: "GET /v2/falcon-sensor/us-2/release/falcon-sensor/blobs/sha256:d5a0125ef6d485c01d5377d4ebe3d74d89ed703a1be60c20529ff5c73a29cc9f HTTP/1.1", subrequest: "/v2/falcon-sensor/us-2/release/falcon-sensor/blobs/sha256:d5a0125ef6d485c01d5377d4ebe3d74d89ed703a1be60c20529ff5c73a29cc9f", upstream: "https://44.241.67.109:443/v2/falcon-sensor/us-2/release/falcon-sensor/blobs/sha256:d5a0125ef6d485c01d5377d4ebe3d74d89ed703a1be60c20529ff5c73a29cc9f", host: "registry.crowdstrike.com"