internal: remove stryker mutation testing (#4163)

currently not actively being used for code quality improvement — if found useful, can be restored

Author: yaacovCR

.eslintignore

@@ -1,6 +1,5 @@
 # Copied from '.gitignore', please keep it in sync.
 /.eslintcache
-/.stryker-tmp
 /node_modules
 /reports
 /npmDist

.github/workflows/mutation-testing.yml

@@ -8,7 +8,6 @@
 /diff-npm-package.html
 /.eslintcache
 /.cspellcache
-/.stryker-tmp
 node_modules
 /reports
 /npmDist

.gitignore

@@ -1,7 +1,6 @@
 # Copied from '.gitignore', please keep it in sync.
 /diff-npm-package.html
 /.eslintcache
-/.stryker-tmp
 /node_modules
 /reports
 /npmDist