RANGER-5764:Enhancing RangerUserStore to include or exclude user group mappings

[abhiishek26]

What changes were proposed in this pull request?

1>Currently, when RangerUserStoreCache refreshes the user store from the database, it always attempts to load user-to-group mappings. In large deployments with a high number of users and groups, loading these mappings on every refresh can significantly increase overhead .

2>I have made it to flag based approach , if flag is set to true then the mappings to the plugins will be provided by the UserStore download apis else not .

3>The major cause of performance bottleneck was final Map<String, Set> userGroups = xUserMgr.getUserGroups();
which has been changed to
final Map<String, Set> userGroups = downloadUserGroupsEnabled ? xUserMgr.getUserGroups() : new HashMap<>();
so based on the requirements we can download or skip user-group mappings in UserStore for Plugins

How was this patch tested?

1>For performance testing this patch was tested for 1 million users and .5 million groups where every 2 user was mapped to one group creating .5 million mappings
2>mvn clean test and mvn clean install were performed locally

[vikaskr22]

@abhiishek26 , please check if you have used the correct JIRA ID in the commit.

[mneethiraj]

I suggest renaming the property to ranger.admin.userstore.include.usergroups.mappings.

[abhiishek26]

Thanks @mneethiraj , I have updated it

[spolavarpau1]

@abhiishek26 , can you also update the title of the commit with correct jira number? (https://issues.apache.org/jira/browse/RANGER-5764)

[abhiishek26]

@abhiishek26 , please check if you have used the correct JIRA ID in the commit.

Thanks Vikas , Sorry it was a mismatch

[abhiishek26]

@abhiishek26 , can you also update the title of the commit with correct jira number? (https://issues.apache.org/jira/browse/RANGER-5764)

Thanks @spolavarpau1 , I have updated it