Fix lunch choices for git_main

We add "trunk_staging-" for all COMMON_LUNCH_CHOICES so they are
valid in the trunk stable setup.

Bug: 308429230
Test: lunch
Merged-In: I59f0d19756f280ad71e3a0755a6c2ccc62f5060c
Change-Id: I59f0d19756f280ad71e3a0755a6c2ccc62f5060c
1 file changed