fix(storybook): incorrect use of theme mixin (#12145)

### Related Ticket(s)

No ticket. Just quick clean up that I couldn't unsee.

### Description

The use of the `theme.theme` mixin from the `@carbon/styles` package (which is forwarded from `@carbon/themes`) was incorrect. The [second argument is meant to be a map of component tokens](https://github.com/carbon-design-system/carbon/blob/main/packages/themes/scss/_theme.scss#L28). We [already add the set of component tokens we want as includes](https://github.com/carbon-design-system/carbon-for-ibm-dotcom/blob/main/packages/web-components/.storybook/container.scss#L20-L22), and therefore don't need the second argument at all. As it was it produced a `--cds-true:;` CSS variable that was useless in the compiled CSS:

![image](https://github.com/user-attachments/assets/72f0342c-b10a-42f5-a183-019d6964a059)


### Changelog

**Changed**

- Fixed incorrect use of `theme.theme` mixin from `@carbon/styles` package

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<!-- *** "test: e2e": Codesandbox examples and e2e integration tests -->
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packages/web-components/.storybook/container.scss

@@ -1,7 +1,7 @@
 //
 // @license
 //
-// Copyright IBM Corp. 2020, 2021
+// Copyright IBM Corp. 2020, 2024
 //
 // This source code is licensed under the Apache-2.0 license found in the
 // LICENSE file in the root directory of this source tree.
@@ -25,28 +25,28 @@
 @include grid.flex-grid();
 
 :root {
-  @include theme($white, true);
+  @include theme($white);
 
-  height: 100%;
+  block-size: 100%;
 }
 
 :root[storybook-carbon-theme='g10'] {
-  @include theme($g10, true);
+  @include theme($g10);
 }
 
 :root[storybook-carbon-theme='g90'] {
-  @include theme($g90, true);
+  @include theme($g90);
 }
 
 :root[storybook-carbon-theme='g100'] {
-  @include theme($g100, true);
+  @include theme($g100);
 }
 
 body {
   // `@include css-body` has `font-family: inherit` via `@include type-style('body-short-01')`,
   // which kills `font-family` from `@include carbon--type-reset`
-  color: $text-primary;
   background-color: $background;
+  color: $text-primary;
   line-height: 1;
 }
 
@@ -71,6 +71,5 @@ html {
 }
 
 .c4d-story-padding {
-  padding-top: $spacing-05;
-  padding-bottom: $spacing-05;
+  padding-block: $spacing-05;
 }