fix(testing): do not inherit existing env (#30688)

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## Current Behavior
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Inheriting the existing environment variable here causes tests to fail
for some reason.

## Expected Behavior
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This reverts it to how it functioned before and fixes the failing tests.

## Related Issue(s)
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merged. -->

Fixes #

nx.json

@@ -245,7 +245,7 @@
   "nxCloudId": "62d013ea0852fe0a2df74438",
   "nxCloudUrl": "https://staging.nx.app",
   "parallel": 1,
-  "bust": 6,
+  "bust": 7,
   "defaultBase": "master",
   "conformance": {
     "rules": [

packages/jest/src/plugins/plugin.ts

@@ -253,11 +253,7 @@ async function buildJestTargets(
   const targets: Record<string, TargetConfiguration> = {};
   const namedInputs = getNamedInputs(projectRoot, context);
 
-  const existingTsNodeCompilerOptions = process.env['TS_NODE_COMPILER_OPTIONS'];
   const tsNodeCompilerOptions = JSON.stringify({
-    ...(existingTsNodeCompilerOptions
-      ? JSON.parse(existingTsNodeCompilerOptions)
-      : {}),
     moduleResolution: 'node10',
     module: 'commonjs',
     customConditions: null,