chore(tests): Remove hard-coded gas limits from system contract tests

Could we add an issue and try to remove the hardcode value in follow-up PRs?

_Originally posted by @LouisTsai-Csie in https://github.com/ethereum/execution-specs/pull/2989#discussion_r3457025425_

Also fix: https://github.com/ethereum/execution-specs/pull/3070#discussion_r3511427154

Start by locating the system contract tests and their hard-coded gas limits, then review the discussions in PRs 2989 and 3070 for the affected cases. The work is complete when those tests no longer rely on hard-coded gas limits and the test suite passes.

Written by the indexing model from the issue text.