[SPARK-11792] remove blockManager from BytesToBytesMap

[davies]

BytesToBytesMap will be used by UnsafeHashRelation, and stored in memory store, then SizeEstimator will see BlockManager as part of BytesToBytesMap, which is not what we expect.

This PR remove the reference to BlockManager in BytesToBytesMap, using SparkEnv.get().blockManager during spilling (currently we get the blockManager in one of the constructors).

cc @yhuai @rxin

[SparkQA]

Test build #46191 has finished for PR 9799 at commit 907ec97.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[JoshRosen]

Just curious: might it be less brittle to implement the new size estimation interface instead, since we should be able to figure out the size exactly?

[andrewor14]

+1 to @JoshRosen's suggestion, which is actually @davies' original proposal. Even though we don't use broadcast BytesToBytesMap currently I think it's still a good guard against potential issues. This patch in its current state actually removes some test logic, which can be avoided if we provide a precise estimate ourselves instead.

[davies]

Since this is not the approach everybody like, and SPARK-11792 is already resolved, I'd close this PR for now.