Merge AutofillTable::kMaxDataLength definitions

By splitting AddressAutofillTable off of AutofillTable,
AutofillTable::kMaxDataLength was duplicated. This CL moves this
constant + a function to truncate strings to that length into
autofill_table_util.h instead.

The constant is renamed to kMaxDataLengthForDatabase.

Bug: 1508865
Change-Id: Ife1dfa562161f35a306845ccfbde25f33d5cfb43
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5116692
Reviewed-by: Jihad Hanna <jihadghanna@google.com>
Reviewed-by: Marc Treib <treib@chromium.org>
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Commit-Queue: Florian Leimgruber <fleimgruber@google.com>
Cr-Commit-Position: refs/heads/main@{#1238709}