Bug 1648430 - Don't run glean tests to fix ccov builds r=firefox-build-system-reviewers,rstewart

For ccov builds, rust tests are ran with `-Cpanic=abort -Zpanic_abort_tests`
and some glean tests are testing panics so in order to have ccov builds we must disable them.

Differential Revision: https://phabricator.services.mozilla.com/D81369

toolkit/library/rust/moz.build

@@ -11,12 +11,16 @@ RustLibrary('gkrust', gkrust_features, is_gkrust=True)
 # Target directory doesn't matter a lot here, since we can't share panic=abort
 # compilation artifacts with gkrust.
 RUST_TESTS = [
-    'glean',
     'selectors',
     'servo_arc',
     'stylo_tests',
 ]
 
+if not CONFIG['MOZ_CODE_COVERAGE']:
+    # glean tests are disabled for ccov builds because some of them test panics
+    # and those builds are compiled with '-Cpanic=abort -Zpanic_abort_tests'
+    RUST_TESTS += ['glean']
+
 for feature in gkrust_features:
     # We don't want to enable refcount logging during rusttests, since the
     # relevant FFI symbols wouldn't be found.