Merge #17455: tests: Update valgrind suppressions

Summary:
Backport PR17455

Backport note:
I've run the same generator and the only thing it turns up currently
is the LogInstance reachable leak (which is intentional, see logger.cpp).
However it's likely we'll see the other reachable leaks appear in
future backports, so might as well include them now.

Note that --child-silent-after-fork=yes is necessary on all valgrind
test_bitcoin runs after D5254, so comments have been updated accordingly.

Result valgrinding test_bitcoin shows no leaks after suppressions:

==28408== HEAP SUMMARY:
==28408==     in use at exit: 1,088 bytes in 5 blocks
==28408==   total heap usage: 182,020,544 allocs, 182,020,539 frees, 31,333,403,759 bytes allocated

We do have some leaks in bench-bitcoin CoinSelection test, likely
need PR14822.

Depends on D5254

Test Plan:
Borrowed from the PR -- run from build dir

valgrind --suppressions=../contrib/valgrind.supp --child-silent-after-fork=yes src/test/test_bitcoin
valgrind --suppressions=../contrib/valgrind.supp src/bench/bitcoin-bench -evals=1 -scaling=0.0

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D5251