fix(firestore): revert changes to isLessThan, isLessThanOrEqualTo,isGreaterThan, isGreaterThanOrEqualTo & arrayContains. null is not valid..

[russellwheatley]

Description

Fixes the linked issue, I double checked on android. These queries isLessThan, isLessThanOrEqualTo,isGreaterThan, isGreaterThanOrEqualTo & arrayContains are all marked @NotNull for the values. See example:

Related Issues

fixes #12003

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