Reduce the scope of the legacy gcp secrets

[fr4nc1sc0-r4m0n]

What does this PR do?

This PR aims to reduce the scope of the legacy kv/ci-shared/observability-ingest/cloud/gcp secret only for the integration-test-matrix pipeline.
This is part of the global process about removing this secret usage.

Why is it important?

It allows us to simplify the pre-command script and to limit the usage of a legacy secret which will be removed in the future.

Checklist

• I have read and understood the pull request guidelines of this project.
• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in ./changelog/fragments using the changelog tool
• I have added an integration test or an E2E test

Disruptive User Impact

How to test this PR locally

Related issues

• This is part of: https://github.com/elastic/observability-robots/issues/2800

Questions to ask yourself

• How are we going to support this in production?
• How are we going to measure its adoption?
• How are we going to debug this?
• What are the metrics I should take care of?
• ...

[mergify]

This pull request does not have a backport label. Could you fix it @fr4nc1sc0-r4m0n? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-./d./d is the label that automatically backports to the 8./d branch. /d is the digit
• backport-active-all is the label that automatically backports to all active branches.
• backport-active-8 is the label that automatically backports to all active minor branches for the 8 major.
• backport-active-9 is the label that automatically backports to all active minor branches for the 9 major.

[fr4nc1sc0-r4m0n]

Some tests are failing but they do not appear to be related with this change

[elasticmachine]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: 1a3bd72

Failed CI Steps

• x86_64:sudo: default

History

• 💔 Build #29467 failed 822f89e
• 💔 Build #29436 failed f9578a3
• 💛 Build #29313 was flaky 9a5b5d9
• 💛 Build #29240 was flaky 2607890
• 💔 Build #29188 failed 6536db8
• 💔 Build #29152 failed 3df2b36

cc @fr4nc1sc0-r4m0n

[github-actions]

@Mergifyio backport 8.19 9.1 9.2

[mergify]

backport 8.19 9.1 9.2

✅ Backports have been created

• #10903 [8.19] (backport #10734) Reduce the scope of the legacy gcp secrets has been created for branch 8.19
• #10904 [9.1] (backport #10734) Reduce the scope of the legacy gcp secrets has been created for branch 9.1
• #10905 [9.2] (backport #10734) Reduce the scope of the legacy gcp secrets has been created for branch 9.2

[v1v]

@fr4nc1sc0-r4m0n , forgot to mention that anytime we touch any CI related things, we need to backport to all the active branches - that's the default behaviour.

For such I added the backport-active-all label,

In some cases we need to be a bit picky and only backport to some branches, btut default it's always to all the active branches