Alerting: Prevent search from locking the browser

[gillesdemey]

This PR prevents the following scenarios:

1. very long search strings from exploding the regex permutations
2. a large amount of search terms (whitespace separated) from locking the browser

[leeoniya]

i would suggest tweaking this further.

for the use case linked in the issue, searching for node_namespace_pod_container:container_cpu_usage_seconds_total:sum_irate was clearly copy-pasted. no one typed this out.

i would recommend detecting such cases and using a different uFuzzy instance configured with the default intraMode: 0 to avoid incurring the cost of trying to match that monstrosity while accounting for spelling mistakes -- intraMode: 1 will needlessly construct a huge regexp here, even without permutations.

[sidewinder12s]

i would suggest tweaking this further.

for the use case linked in the issue, searching for node_namespace_pod_container:container_cpu_usage_seconds_total:sum_irate was clearly copy-pasted. no one typed this out.

i would recommend detecting such cases and using a different uFuzzy instance configured with the default intraMode: 0 to avoid incurring the cost of trying to match that monstrosity while accounting for spelling mistakes -- intraMode: 1 will needlessly construct a huge regexp here, even without permutations.

Correct, I had copy pasted it when I ran into some of these locking issues.

[soniaAguilarPeiron]

code changes LGTM!

[ryan-grafana]

Approved to back port