fix(overflow-menu): position jumping (#11448)

### Related Ticket(s)

Closes #9827 

### Description

the `refBottom` needs to be compared to the `containerTop`, so that the menu sticks to the bottom of button

Example (using local `yarn pack`:
https://codesandbox.io/p/devbox/test-overflowmenu-t4slfp?file=%2F.codesandbox%2Ftasks.json%3A1%2C241
live demo: https://t4slfp-9000.csb.app/
### Changelog

**New**

- {{new thing}}

**Changed**

- changed `refBottom` to a let and then equal `refBottom = refBottom - containerTop;`
- ^ wondering if this can be cleaned up code wise, but testing locally with overflow-menu it seems successful

**Removed**

- {{removed thing}}

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packages/carbon-web-components/src/components/floating-menu/floating-menu.ts

@@ -1,7 +1,7 @@
 /**
  * @license
  *
- * Copyright IBM Corp. 2019, 2023
+ * Copyright IBM Corp. 2019, 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.
@@ -187,14 +187,15 @@ abstract class CDSFloatingMenu extends HostListenerMixin(
       left: refLeft = 0,
       top: refTop = 0,
       right: refRight = 0,
-      bottom: refBottom = 0,
     } = triggerPosition;
+    let { bottom: refBottom = 0 } = triggerPosition;
     const { width, height } = this.getBoundingClientRect();
     const {
       left: containerLeft = 0,
       right: containerRight = 0,
       top: containerTop = 0,
     } = container.getBoundingClientRect();
+    refBottom = refBottom - containerTop;
 
     const containerComputedStyle =
       container.ownerDocument!.defaultView!.getComputedStyle(container);