BREAKING: refactor(bundle): Remove bundle manifest

[simar7]

Remove manifest file. It's optional and we are not using it for any meaningful purpose.

Related PR: aquasecurity/trivy#8533

[simar7]

@nikpivkin this would be a breaking change for older Trivy versions as not having a manifest results in an error as seen in the tests:

    check_examples_test.go:95: 2025-03-14T02:44:36Z	INFO	[misconfig] Misconfiguration scanning is enabled
        2025-03-14T02:44:36Z	INFO	[misconfig] Need to update the built-in checks
        2025-03-14T02:44:36Z	INFO	[misconfig] Downloading the built-in checks...
        140.81 KiB / 140.81 KiB [------------------------------------------------------] 100.00% ? p/s 100ms2025-03-14T02:44:36Z	ERROR	[misconfig] Falling back to embedded checks	err="check load error: manifest file open error (/root/.cache/trivy/policy/content/.manifest): open /root/.cache/trivy/policy/content/.manifest: no such file or directory"

Fortunately our bundle is versioned so we could update our bundle major version, but doing that to me as the only change in the version is a bit excessive. Maybe we simply wait before we remove the manifest from the bundle, or do you have any other ideas?

[nikpivkin]

@simar7 I don't think this change gives us anything and so it can wait. We can come back to it when we are going to release the next major version of the bundle.

[nikpivkin]

The way the bundle is built has changed, so I opened a new PR #485

[simar7]

Closing in favour of #485