fix(GlFilteredSearch): Fix clear button overlapping long text & input

What does this MR do?

Add styles overflow-hidden & padding-right to original scrollable div.

Adds child div with overflow-auto which scrolls.

First approach (Not used anymore)

Adds fix in `GlSearchboxByClick` by removing absolute style on the `GlClearIconButton`

Instead, this MR renders the button within a container in the append slot so that the button is not part of the gl-filtered-search-scrollable container.

Additionally adjusts left padding for first gl-filtered-search-item

Does this MR meet the acceptance criteria?

Before	after

Conformity

• Code review guidelines.
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• Added the ~"component:*" label(s) if applicable.

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
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Accessibility

If this MR adds or modifies a component, take a few moments to review the following:

• All actions and functionality can be done with a keyboard.
• Links, buttons, and controls have a visible focus state.
• All content is presented in text or with a text equivalent. For example, alt text for SVG, or aria-label for icons that have meaning or perform actions.
• Changes in a component’s state are announced by a screen reader. For example, changing aria-expanded="false" to aria-expanded="true" when an accordion is expanded.
• Color combinations have sufficient contrast.

Closes #2226 (closed)