Fix ManifestMerger issues

Set LOCAL_MIN_SDK_VERSION in SettingsLib so that the build system
doesn't raise the minSdkVersion value specified in the manifest,
which causes ManifestMerger to error when trying to merge it into
a package that specifies a lower minSdkVersion.

Bug: 78447299
Test: m java
Change-Id: Ie2c2458647cd6495418999b35894dc92343992cc