[HUDI-7238] Bug fixes and optimization of ExternalSpillableMap

[the-other-tim-brown]

Change Logs

• The ExternalSpillableMap is now marked as Closeable as a reminder to developers that it needs to be closed and so we can use try-with-resources with this object
• Even when there was no data stored externally, the code would create an external map for functions like isEmpty which will cause unnecessary overhead and more cleanup when calling close. This change adds an "Empty" BitMap that will be used if the BitMap is not yet initialized
• A few places were missing calls to close the map, so those are updated as well. The shutdown hook will now log as well so any other places can more easily be detected

Impact

Avoids leaks from not closing the ExternalSpillableMap and optimize case where all data for that map is currently in memory.

Risk level (write none, low medium or high below)

If medium or high, explain what verification was done to mitigate the risks.

Documentation Update

Describe any necessary documentation update if there is any new feature, config, or user-facing change

• The config description must be updated if new configs are added or the default value of the configs are changed
• Any new feature or user-facing change requires updating the Hudi website. Please create a Jira ticket, attach the ticket number here and follow the instruction to make changes to the website.

Contributor's checklist

• [ ] Read through contributor's guide
• [ ] Change Logs and Impact were stated clearly
• [ ] Adequate tests were added if applicable
• [ ] CI passed

[hudi-bot]

CI report:

• 9c2e36ff019825e1b3e208e7a8ae0d0252029ea3 Azure: SUCCESS

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