Remove unused InputMethodSettings#{get,put}Boolean()

This is a follow up to my previous CLs [1][2], which inlined the
following methods

 - InputMethodSettings#isShowImeWithHardKeyboardEnabled()
 - InputMethodSettings#setShowImeWithHardKeyboardEnabled()

As a result, we can also remove the following methods.

 - InputMethodSettings#getBoolean()
 - InputMethodSettings#setBoolean()

as they are no longer used.

There must be no observable behavior change in this CL.

 [1]: I52cf78b95b8514844a0aa88406683ea0f6e88ad9
      47f311b2
 [2]: I0c3e0e16f361dff84c3b79040a9a83058512088f
      e5468607

Bug: 309868254
Bug: 309837937
Test: presubmit
Change-Id: I2c62e25bd77381a73c253e186bb5976ac68d6c73