test: remove confusing MAX_BLOCK_BASE_SIZE

The constant `MAX_BLOCK_BASE_SIZE` has been removed from the
core implementation years ago due to being confusing and
superfluous, as it is implied by the block weight limit (see
PRs #10618 and #10608). Since there is also no point in
still keeping it in the functional test framework, we switch
to weight-based accounting on the relevant test code parts
and use `MAX_BLOCK_WEIGHT` instead for the block limit
checks.

test/functional/test_framework/messages.py

@@ -32,7 +32,7 @@ from test_framework.siphash import siphash256
 from test_framework.util import hex_str_to_bytes, assert_equal
 
 MAX_LOCATOR_SZ = 101
-MAX_BLOCK_BASE_SIZE = 1000000
+MAX_BLOCK_WEIGHT = 4000000
 MAX_BLOOM_FILTER_SIZE = 36000
 MAX_BLOOM_HASH_FUNCS = 50