Populate binder trace txn names lazily

Previously, for each binder interface, we populated a cache of all
txn codes to names on the first binder txn to that interface. This
skewed the binder txn latency significantly for the first txn to an
interface.

Now, we lazily populate the cache on each new binder txn.

Test: atest open-prebuilt-calculator --rebuild-module-info
--tf-template metric_post_processor=
google/template/postprocessors/metric-file-aggregate.xml
(neglible startup time diff locally)
Bug: 246650647

Change-Id: Ib569ebe34e7ef6bb4fa6e53defedcb33ed824308
Merged-In: Ib569ebe34e7ef6bb4fa6e53defedcb33ed824308