fix(core): remove unused getTerminalOutput from BatchProcess (#34604)

## Current Behavior

`BatchProcess` accumulates all stdout/stderr output in
`terminalOutputChunks` and exposes it via `getTerminalOutput()`, but
nothing ever calls `getTerminalOutput()`. The accumulated strings are
unique allocations (created via `chunk.toString()`), not shared with the
output callbacks or `process.stdout.write`.

For verbose batched tasks (e.g., Maven/Gradle with hundreds of tasks),
this can hold tens to hundreds of MB for the entire batch duration.

## Expected Behavior

Remove the dead accumulation code. stdout/stderr chunks are still
forwarded to `process.stdout`/`process.stderr` and output callbacks as
before — only the unused storage is removed.

---------

Co-authored-by: nx-cloud[bot] <71083854+nx-cloud[bot]@users.noreply.github.com>

Author: leosvelperez

packages/nx/src/tasks-runner/running-tasks/batch-process.ts

@@ -14,8 +14,6 @@ export class BatchProcess {
     (task: string, result: TaskResult) => void
   > = [];
   private outputCallbacks: Array<(output: string) => void> = [];
-  private terminalOutputChunks: string[] = [];
-  private joinedTerminalOutput: string | undefined;
 
   constructor(
     private childProcess: ChildProcess,
@@ -59,7 +57,6 @@ export class BatchProcess {
     if (this.childProcess.stdout) {
       this.childProcess.stdout.on('data', (chunk) => {
         const output = chunk.toString();
-        this.terminalOutputChunks.push(output);
 
         // Maintain current terminal output behavior
         process.stdout.write(chunk);
@@ -75,7 +72,6 @@ export class BatchProcess {
     if (this.childProcess.stderr) {
       this.childProcess.stderr.on('data', (chunk) => {
         const output = chunk.toString();
-        this.terminalOutputChunks.push(output);
 
         // Maintain current terminal output behavior
         process.stderr.write(chunk);
@@ -134,9 +130,4 @@ export class BatchProcess {
       this.childProcess.kill(signal);
     }
   }
-
-  getTerminalOutput(): string {
-    this.joinedTerminalOutput ??= this.terminalOutputChunks.join('');
-    return this.joinedTerminalOutput;
-  }
 }