Make the Brew automation depend on trigger files.

**What would you like to be added**:
Today we update the aws tap repo for brew by having a trigger file pull down the latest bundle and use the release versions and checksums. However this does not alway hold true that the brew PR made is for the latest minor or patch version. We should be instead reading from the brew trigger [file](https://github.com/aws/eks-anywhere/blob/main/release/triggers/brew-version-release/CLI_RELEASE_VERSION) and pulling down manifests for that specific release.

Read release/triggers/brew-version-release/CLI_RELEASE_VERSION first, then trace the Brew automation that updates the aws tap. Done means the automation selects manifests for the release named in that trigger file, including its release version and checksums, so the resulting Brew PR targets that specific release.

Written by the indexing model from the issue text.