fix(animations): @internal must use JSDoc tags. (#24928)

This change fixes up several comments that accidentally used the JSDoc
tag @internal in regular block comments (`/*` instead of `/**`).

This prevents a problem with Closure Compiler that balks at `@` tags
occuring in regular block comments, because it assumes they were
intended to be tags for the compiler.

When occuring in `/**` JSDoc, tsickle escapes the tags, so they do not
cause problems.

PR Close #24928

packages/animations/browser/src/render/css_keyframes/css_keyframes_player.ts

@@ -124,7 +124,7 @@ export class CssKeyframesPlayer implements AnimationPlayer {
         DEFAULT_FILL_MODE, () => this.finish());
   }
 
-  /* @internal */
+  /** @internal */
   triggerCallback(phaseName: string): void {
     const methods = phaseName == 'start' ? this._onStartFns : this._onDoneFns;
     methods.forEach(fn => fn());

packages/animations/browser/src/render/transition_animation_engine.ts

@@ -1514,7 +1514,7 @@ export class TransitionAnimationPlayer implements AnimationPlayer {
 
   getPosition(): number { return this.queued ? 0 : this._player.getPosition(); }
 
-  /* @internal */
+  /** @internal */
   triggerCallback(phaseName: string): void {
     const p = this._player as any;
     if (p.triggerCallback) {

packages/animations/browser/src/render/web_animations/web_animations_player.ts

@@ -155,7 +155,7 @@ export class WebAnimationsPlayer implements AnimationPlayer {
     this.currentSnapshot = styles;
   }
 
-  /* @internal */
+  /** @internal */
   triggerCallback(phaseName: string): void {
     const methods = phaseName == 'start' ? this._onStartFns : this._onDoneFns;
     methods.forEach(fn => fn());