Optimize string matching

[brancz]

Improves performance by ~4x or more.

$ benchstat old.txt new.txt
goos: darwin
goarch: arm64
pkg: github.com/parca-dev/parca/pkg/query
cpu: Apple M1 Max
                                               │   old.txt    │               new.txt                │
                                               │    sec/op    │    sec/op     vs base                │
StringMatching/equalFoldBytes-10                 58.745n ± 1%   2.923n ±  7%  -95.02% (p=0.000 n=10)
StringMatching/containsFoldBytes-10               69.07n ± 7%   18.68n ±  3%  -72.95% (p=0.000 n=10)
StringMatching/hasPrefixFoldBytes-10              62.72n ± 2%   10.06n ± 13%  -83.96% (p=0.000 n=10)
StringMatchingLongStrings/containsFoldBytes-10   203.30n ± 2%   55.16n ±  2%  -72.87% (p=0.000 n=10)
geomean                                           84.81n        13.19n        -84.44%

[alwaysmeticulous]

✅ Meticulous spotted 0 visual differences across 338 screens tested: view results.

Meticulous evaluated ~4 hours of user flows against your PR.

_{Expected differences? Click here. Last updated for commit cdb3c82. This comment will update as new commits are pushed.}

[yomete]

lgtm