[Feature] Use by default semantical branch name "release/*" for releases

[lisachenko]

Is your feature request related to a problem? Please describe.
Current release-please branch name doesn't follow the Conventional Branch names standard for releases: like release/* which can be be improved.

Describe the solution you'd like
Conventional Branches standard suggests to use the release/* branch name prefix for releases, for example, release/v1.2.3, see below:

release/: For branches preparing a release (e.g., release/v1.2.0)

Would be nice to follow this specification and adjust the default branch prefix name to follow this standard.

Describe alternatives you've considered
None, just matter of improving compliance with ITGC/ISO27001 standards

Additional context
Depends on #1167 to make branch prefix configurable