Infer project from issuable parameter in issuable_meta helper

The following discussion from !92738 (merged) should be addressed:

@splattael started a discussion:
Suggestion (non-blocking)

While reviewing the specs I realized that we could infer project from issuable rendering the parameter project superfluous.

WDYT of:
```
  def issuable_meta(issuable)
    project = issuable.project
```