fix(avatar): fix avatar tokens on ionic theme (#30438)

Issue number: internal

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## What is the new behavior?
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this PR. -->

- Review background color token and xxsmall size

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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## Other information

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screenshots of how the component looks before and after the change. -->

[Avatar ionic
theme](https://ionic-framework-git-rou-11968-avatar-ionic1.vercel.app/src/components/avatar/test/size?ionic:theme=ionic)

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Co-authored-by: ionitron <hi@ionicframework.com>

core/src/components/avatar/avatar.ionic.scss

@@ -15,7 +15,7 @@
   align-items: center;
   justify-content: center;
 
-  background: globals.$ion-bg-neutral-subtlest-default;
+  background: globals.$ion-bg-neutral-subtle-default;
   color: globals.$ion-text-subtlest;
 }
 
@@ -118,6 +118,11 @@
   @include globals.padding(0);
 }
 
+:host(.avatar-xxsmall) ::slotted(ion-icon) {
+  width: globals.$ion-scale-300;
+  height: globals.$ion-scale-300;
+}
+
 :host(.avatar-xsmall) ::slotted(ion-icon) {
   width: globals.$ion-scale-400;
   height: globals.$ion-scale-400;
@@ -134,13 +139,13 @@
 }
 
 :host(.avatar-large) ::slotted(ion-icon) {
-  width: globals.$ion-scale-800;
-  height: globals.$ion-scale-800;
+  width: globals.$ion-scale-700;
+  height: globals.$ion-scale-700;
 }
 
 :host(.avatar-xlarge) ::slotted(ion-icon) {
-  width: globals.$ion-scale-1000;
-  height: globals.$ion-scale-1000;
+  width: globals.$ion-scale-800;
+  height: globals.$ion-scale-800;
 }
 
 // Avatar Badge Empty (hint)