Outdated default timeout in rule-file-perf-principles

[jkylekelly]

Currently, https://semgrep.dev/docs/kb/rules/rule-file-perf-principles states:

The time for matching is number of files * time to match each file. The time to check each file can also grow, in the worst case, exponentially, especially when a rule has a lot of matches in subpatterns. However, the default settings of --timeout 30 --timeout-threshold 3 means that a file times out if:
30 seconds elapse without the match process completing
3 rules time out

However, the default --timeout assignment is 5s and not 30s.

[s-santillan]

@khorne3 this is your bebe!
Thanks @jkylekelly for the heads up.