Correctly parse minSdk even when targetSdk is a codename

The code that assigned target to min if min was not specified was
only checking for min codenames, but if the manifest specified a
numerical minSdkVersion, that is valid and would incorrectly prevent
the package from installing.

Bug: 237059024

Test: mts-tradefed > mts-eng-only -m ApkInApexTest

Change-Id: I3a2b9baa82ebb8ca9031c9fa128ce12bff17226e