Fix incorrect checkout parameter names + string truncation script

[MiYanni]

Summary

From merging this, I had updated the parameter names for checkout from engBranch and sourceBranch to engBranchAlias and sourceBranchAlias to be more representative of their usage. This didn't align with the changes for doing an insertion stage, so the insertion stage was failing. This updates the parameter names appropriately.

Additionally, this fixes the string truncation issue for the commit message script.

Errors

Parameter issue

Encountered error(s) while parsing pipeline YAML:
/v1/Jobs/SDLSourceAnalysisJobInternal.yml@1esPipelines (Line: 152, Col: 13): Unexpected value 'The repository ""eng"" to be checked out has not been specified under sdl.sourceRepositoriesToScan.include or sdl.sourceRepositoriesToScan.exclude. For more information, visit https://aka.ms/1espt/multi-repo-sdl'
__built-in-schema.yml (Line: 1332, Col: 19): Object reference not set to an instance of an object.
/v1/1ES.Official.PipelineTemplate.yml@1esPipelines: Object reference not set to an instance of an object.
__built-in-schema.yml (Line: 34, Col: 9): Object reference not set to an instance of an object.
/eng/pipelines/official.yml: Object reference not set to an instance of an object.

Commit message script issue

Exception calling "Substring" with "2" argument(s): "Index and length must refer to a location within the string.
Parameter name: length"
At D:\a\_work\_temp\6d6a39b7-c40e-43cd-a0d8-12028d0fa97c.ps1:8 char:22
+ $commitMessage = ("$(git log -1 --pretty=%s)".Trim() -replace '["\/:< ...
+                      ~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], ParentContainsErrorRecordException
    + FullyQualifiedErrorId : ArgumentOutOfRangeException