Consolidate redundant Darwin test scripts (#26366)

Remove redundant Darwin ARM testing scripts, as we now only test Darwin
on ARM.

The consolidated versions should cover the union of what was covered by
the previous ones.

Resolves Cray/chapel-private#6880.

[reviewed by @tzinsky and @arezaii , thanks!]

util/cron/test-darwin.bash

@@ -1,11 +1,12 @@
 #!/usr/bin/env bash
 #
-# Test examples for default configuration on darwin
+# Test full suite for default configuration on darwin
 
 UTIL_CRON_DIR=$(cd $(dirname ${BASH_SOURCE[0]}) ; pwd)
 source $UTIL_CRON_DIR/common.bash
 source $UTIL_CRON_DIR/common-darwin.bash
+source $UTIL_CRON_DIR/common-localnode-paratest.bash
 
 export CHPL_NIGHTLY_TEST_CONFIG_NAME="darwin"
 
-$UTIL_CRON_DIR/nightly -cron -examples -blog
+$UTIL_CRON_DIR/nightly -cron -blog $(get_nightly_paratest_args)

util/cron/test-gasnet.darwin.bash

@@ -1,11 +1,12 @@
 #!/usr/bin/env bash
 #
-# Test gasnet (segment everything) against example tests
+# Test gasnet (segment everything) against multilocale tests on darwin
 
 UTIL_CRON_DIR=$(cd $(dirname ${BASH_SOURCE[0]}) ; pwd)
 source $UTIL_CRON_DIR/common-gasnet.bash
 source $UTIL_CRON_DIR/common-darwin.bash
+source $UTIL_CRON_DIR/common-localnode-paratest.bash
 
 export CHPL_NIGHTLY_TEST_CONFIG_NAME="gasnet.darwin"
 
-$UTIL_CRON_DIR/nightly -cron -examples
+$UTIL_CRON_DIR/nightly -cron -multilocale $(get_nightly_paratest_args)

util/cron/test-gasnet.fast.darwin.bash

@@ -1,12 +1,13 @@
 #!/usr/bin/env bash
 #
-# Test gasnet (segment fast) against hellos on darwin
+# Test gasnet (segment fast) against multilocale tests on darwin
 
 UTIL_CRON_DIR=$(cd $(dirname ${BASH_SOURCE[0]}) ; pwd)
 source $UTIL_CRON_DIR/common-gasnet.bash
 export CHPL_GASNET_SEGMENT=fast
 source $UTIL_CRON_DIR/common-darwin.bash
+source $UTIL_CRON_DIR/common-localnode-paratest.bash
 
 export CHPL_NIGHTLY_TEST_CONFIG_NAME="gasnet.fast.darwin"
 
-$UTIL_CRON_DIR/nightly -cron -hellos
+$UTIL_CRON_DIR/nightly -cron -multilocale $(get_nightly_paratest_args)