fix(docs-infra): always default to no linenums in <aio-code> (#31674)

Previously, `linenums` defaulted to true if the content was more than 10
lines long and false otherwise.

Since in most cases linenums add unnecessary visual noise, this commit
changes `linenums` to always default to false (regardless of the size of
the content). It can be still be turned on by explicitly setting to true
or a number.

PR Close #31674

aio/src/app/custom-elements/code/code.component.ts

@@ -5,12 +5,6 @@ import { CopierService } from 'app/shared/copier.service';
 import { MatSnackBar } from '@angular/material/snack-bar';
 import { tap } from 'rxjs/operators';
 
-/**
- * If linenums is not set, this is the default maximum number of lines that
- * an example can display without line numbers.
- */
-const DEFAULT_LINE_NUMS_COUNT = 10;
-
 /**
  * Formatted Code Block
  *
@@ -170,9 +164,7 @@ export class CodeComponent implements OnChanges {
       typeof this.linenums === 'string' ? parseInt(this.linenums, 10) :
       this.linenums;
 
-    // if no linenums, enable line numbers if more than one line
-    return linenums == null || isNaN(linenums as number) ?
-        (code.match(/\n/g) || []).length > DEFAULT_LINE_NUMS_COUNT : linenums;
+    return (linenums != null) && !isNaN(linenums as number) && linenums;
   }
 }