test: fix test-linux-perf flakiness

The new V8 seems to be optimizing the functions we use in this test
faster than before. Increasing the sampling frequency for Linux perf
fixes the issue.

PR-URL: https://github.com/nodejs/node/pull/27615
Refs: https://github.com/v8/v8/compare/7.4.288.21...7.4.288.27


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>