fix(GlLabel): Fix label spacing and overflow

What does this MR do?

This MR fixes 2 issues raised in gitlab#216881 (comment 429633299) and gitlab#216881 (comment 429609155):

• The wide spacing between the label title and x button is improved
• A very long label title pushing the x button of visibility is fixed

Screenshots

Spacing fix:

label type	before	after
unscoped
scoped

Overflow fix:

label type	before	after
unscoped
scoped

Does this MR meet the acceptance criteria?

Conformity

• Code review guidelines.
• GitLab UI's contributing guidlines.
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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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