Default group-pull-request-title-pattern prevents release creation on merge

## Bug

When using manifest mode with `separate-pull-requests: false` (the
default), release-please uses `group-pull-request-title-pattern` to
generate the release PR title. The default pattern produces titles
like `chore: release main` — which does not include `${version}`.

When this PR is merged, release-please cannot extract the version
from the title, so it **silently skips creating the GitHub release
and tag**. The manifest gets updated (indicating the release PR was
recognized), but no release is created.

## Steps to reproduce

1. Use manifest config with a single package and default settings:

```json
{
"packages": {
".": {
"release-type": "maven"
}
}
}
```

2. Release-please creates a PR titled `chore: release main`
3. Merge the PR
4. Release-please runs but does not create a tag or GitHub release
5. Logs show:

```
⚠ pullRequestTitlePattern miss the part of '${scope}'
⚠ pullRequestTitlePattern miss the part of '${component}'
⚠ pullRequestTitlePattern miss the part of '${version}'
...
⚠ Expected 1 releases, only found 0
```

## Expected behavior

Either:
- The default `group-pull-request-title-pattern` should include
`${version}` (e.g. `chore${scope}: release${component} ${version}`)
- Or the warnings about missing `${version}` in the title pattern
should be errors that prevent creating a PR that can never result
in a release

## Workaround

Explicitly set the title pattern in config:

```json
{
"group-pull-request-title-pattern": "chore${scope}: release${component} ${version}"
}
```

## Context

Hit this in https://github.com/prometheus/client_java while setting
up release-please with manifest mode. Release PRs were created and
merged successfully but no releases were ever produced. Took
significant debugging to trace it to the title pattern.

Using release-please v17.1.3 via release-please-action v4.4.0.