presets: Update swift macos/linux preset

Update the Swift repo build preset to depend on the
mixin_swiftpm_base preset to ensure it has all the
same presets as SwiftPM.

Also, ensure the Swift macos/linux preset do not
skip the swift-test.

Author: bkhouri

utils/build-presets.ini

@@ -609,8 +609,10 @@ mixin-preset=
     buildbot_incremental_base
     lldb-smoketest,tools=RA
     mixin_buildbot_install_components_with_clang
+    mixin_swiftpm_base
 build-subdir=buildbot_incremental
 
+skip-test-swift=false
 # We build release+asserts.
 release
 assertions
@@ -1077,6 +1079,7 @@ mixin-preset=
 mixin-preset=
     mixin_lightweight_assertions,no-stdlib-asserts
     mixin_linux_installation
+    mixin_swiftpm_base
 build-subdir=buildbot_linux
 lldb
 release
@@ -1094,6 +1097,7 @@ install-swiftformat
 reconfigure
 test-optimized
 skip-test-swiftdocc
+skip-test-swift=false
 
 # gcc version on amazon linux 2 is too old to configure and build tablegen.
 # Use the clang that we install in the path for macros