[AMBARI-22649] settings library should convert true/false to boolean

[adoroszlai]

What changes were proposed in this pull request?

The settings library for getting clusterSettings and stackSettings should convert literal "true" and "false" values to the Python boolean type to retain backward compatibility with ConfigDictionary:

ambari/ambari-common/src/main/python/resource_management/libraries/script/config_dictionary.py

Lines 57 to 62 in 40e5585

	if value == "true":
	value = True
	elif value == "false":
	value = False
	return value

Stack scripts rely on this behavior in a lot of places. One of the most widely used is the security_enabled flag. Without this conversion, scripts would execute the "secure" code path for both "true" and "false" values, since only the empty string is treated as False.

ambari/ambari-server/src/main/resources/common-services/ZOOKEEPER/3.4.5/package/scripts/params_linux.py

Line 96 in 40e5585

security_enabled = config['configurations']['cluster-env']['security_enabled']

ambari/ambari-server/src/main/resources/common-services/ZOOKEEPER/3.4.5/package/scripts/zookeeper.py

Line 99 in 40e5585

if params.security_enabled:

How was this patch tested?

Deployed cluster using blueprint.

Unit test tweaked, passing:

$ mvn -am -pl ambari-server -Del.log=WARN -DfailIfNoTests=false -DskipSurefireTests -Dcheckstyle.skip -Drat.skip -Dpython.test.mask=TestSettings.py test
...
Total run:14
Total errors:0
Total failures:0
OK

[asfgit]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/Ambari-Github-PullRequest-Builder/722/
Test FAILed.
Test FAILured.

[mradha25]

LGTM