fix(content-block-mixed): remove conflicting element IDs (#8219)

### Related Ticket(s)

Resolves #8011 

### Description

Design programs often automatically add IDs to image layers when exporting as SVG. In our case, these IDs do not serve a purpose, and removing them resolves some errors reported by the `yarn test:a11y` script.

### Changelog

**Changed**

- Removed `id` attributes from SVG layers in the `dds-content-block-mixed` stories.
- Removed `id` attributes from SVG layers in the `dds-content-group-pictogram` stories.

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packages/web-components/src/components/content-block-mixed/__stories__/content-block-mixed.stories.ts

@@ -2,7 +2,7 @@
 /**
  * @license
  *
- * Copyright IBM Corp. 2020, 2021
+ * Copyright IBM Corp. 2020, 2022
  *
  * This source code is licensed under the Apache-2.0 license found in the
  * LICENSE file in the root directory of this source tree.
@@ -181,8 +181,8 @@ export const Default = ({ parameters }) => {
                 viewBox="8 8 32 32"
                 xml:space="preserve"
               >
-                <g id="touch_screen">
-                  <g id="touch_screen_1_">
+                <g>
+                  <g>
                     <path
                       style="fill:none;stroke-width:0.72;stroke-linejoin:round;stroke-miterlimit:10;"
                       d="M15,29H9V10h25v19h-7
@@ -193,7 +193,7 @@ export const Default = ({ parameters }) => {
                     />
                   </g>
                 </g>
-                <g id="Layer_1"></g>
+                <g></g>
               </svg>
               <dds-content-item-heading>${itemHeading}</dds-content-item-heading>
               <dds-content-item-copy>${itemCopy}</dds-content-item-copy>
@@ -269,8 +269,8 @@ export const WithLinkList = ({ parameters }) => {
                 viewBox="8 8 32 32"
                 xml:space="preserve"
               >
-                <g id="touch_screen">
-                  <g id="touch_screen_1_">
+                <g>
+                  <g>
                     <path
                       style="fill:none;stroke-width:0.72;stroke-linejoin:round;stroke-miterlimit:10;"
                       d="M15,29H9V10h25v19h-7
@@ -281,7 +281,7 @@ export const WithLinkList = ({ parameters }) => {
                     />
                   </g>
                 </g>
-                <g id="Layer_1"></g>
+                <g"></g>
               </svg>
               <dds-content-item-heading>${itemHeading}</dds-content-item-heading>
               <dds-content-item-copy>${itemCopy}</dds-content-item-copy>

packages/web-components/src/components/content-group-pictograms/__stories__/content-group-pictograms.stories.ts

@@ -2,7 +2,7 @@
 /**
  * @license
  *
- * Copyright IBM Corp. 2020, 2021
+ * Copyright IBM Corp. 2020, 2022
  *
  * This source code is licensed under the Apache-2.0 license found in the
  * LICENSE file in the root directory of this source tree.
@@ -103,8 +103,8 @@ export const Default = ({ parameters }) => {
               viewBox="8 8 32 32"
               xml:space="preserve"
             >
-              <g id="touch_screen">
-                <g id="touch_screen_1_">
+              <g>
+                <g>
                   <path
                     style="fill:none;stroke-width:0.72;stroke-linejoin:round;stroke-miterlimit:10;"
                     d="M15,29H9V10h25v19h-7
@@ -115,7 +115,7 @@ export const Default = ({ parameters }) => {
                   />
                 </g>
               </g>
-              <g id="Layer_1"></g>
+              <g></g>
             </svg>
             <dds-content-item-heading>${heading}</dds-content-item-heading>
             <dds-content-item-copy>${copy}</dds-content-item-copy>