Bump controller-runtime to v0.18.5 and k8s libs to v.1.30.3

[fra98]

Description

This PR bumps k8s to v1.30.3 and controller-runtime to v0.18.5 and adds the following fixes:

• skip tests using Server Side Apply (SSA) on fake-client (temporary workaround to be revised after fixed upstream)
• refactor code to support breaking changes introduced in v0.18.x (admission.Decoder is now an interface and WatchRawSource() arguments)

[adamjensenbot]

Hi @fra98. Thanks for your PR!

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[fra98]

/test

[fra98]

/merge