Demote BinderGetCallingInMainThread from an error to a warning

Lint was updated, and adds this new error-level check that we
have preexisting occurances of.

Bug: 247885568
Bug: 249337906
Bug: 249335143
Test: m lint-check on internal master
Change-Id: I88c337dd1e12b2722a97e878b5277201df0c163d
diff --git a/java/lint_defaults.txt b/java/lint_defaults.txt
index bff7221..519a702 100644
--- a/java/lint_defaults.txt
+++ b/java/lint_defaults.txt
@@ -39,6 +39,7 @@
 # Downgrade existing errors to warnings
 --warning_check AppCompatResource                  # 55 occurences in 10 modules
 --warning_check AppLinkUrlError                    # 111 occurences in 53 modules
+--warning_check BinderGetCallingInMainThread
 --warning_check ByteOrderMark                      # 2 occurences in 2 modules
 --warning_check DuplicateActivity                  # 3 occurences in 3 modules
 --warning_check DuplicateDefinition                # 3623 occurences in 48 modules