revert docker build context flag and command line input to generate workflow

[davidgamero]

Description

the -x command is not recognized by acr, and needs to be removed from the generated workflow in order to make valid github workflow files. In its current state, the workflow runs will always fail as this flag isn't recognized.

update call to updateProductionDeployments to use customInputs instead of flagValuesMap as it is a subset that was restricting command line input usage (all keys present in flagValuesMap are in customInputs due to the call to maps.Copy(customInputs, flagValuesMap))

add a nil map check for flagValuesMap

Fixes # (issue)

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[bfoley13]

Revert looks good. Lets come back at this with some E2E tests using repos with a custom build context in the future