Remove border from primary buttons in the toolbar

[ryankeairns]

Summary

2nd attempt at removing the border on the blue, primary button in the shared toolbar.
Previously, I didn't account for the 'text' colored buttons in the Lens toolbar. This time around, I narrowed the issue down to the custom styles being passed down via cssProps and simply ignore them for primary/fill buttons.

Before

After
Dashboard
No gray border on the Create visualization button

Lens
Borders for axis settings remain

Checklist

Delete any items that are not applicable to this PR.

• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• Documentation was added for features that require explanation or tutorials
• Unit or functional tests were updated or added to match the most common scenarios
• Flaky Test Runner was used on any tests changed
• Any UI touched in this PR is usable by keyboard only (learn more about keyboard accessibility)
• Any UI touched in this PR does not create any new axe failures (run axe in browser: FF, Chrome)
• If a plugin configuration key changed, check if it needs to be allowlisted in the cloud and added to the docker list
• This renders correctly on smaller devices using a responsive layout. (You can test this in your browser)
• This was checked for cross-browser compatibility

Risk Matrix

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Before closing this PR, invite QA, stakeholders, and other developers to identify risks that should be tested prior to the change/feature release.

When forming the risk matrix, consider some of the following examples and how they may potentially impact the change:

Risk	Probability	Severity	Mitigation/Notes
Multiple Spaces—unexpected behavior in non-default Kibana Space.	Low	High	Integration tests will verify that all features are still supported in non-default Kibana Space and when user switches between spaces.
Multiple nodes—Elasticsearch polling might have race conditions when multiple Kibana nodes are polling for the same tasks.	High	Low	Tasks are idempotent, so executing them multiple times will not result in logical error, but will degrade performance. To test for this case we add plenty of unit tests around this logic and document manual testing procedure.
Code should gracefully handle cases when feature X or plugin Y are disabled.	Medium	High	Unit tests will verify that any feature flag or plugin combination still results in our service operational.
See more potential risk examples

For maintainers

• This was checked for breaking API changes and was labeled appropriately

[elasticmachine]

Pinging @elastic/appex-sharedux (Team:SharedUX)

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: f5dd137

Metrics [docs]

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
canvas	1.1MB	1.1MB	+15.0B
dashboard	533.6KB	533.6KB	+15.0B
discover	842.4KB	842.4KB	+15.0B
lens	1.5MB	1.5MB	+15.0B
presentationUtil	85.9KB	85.9KB	+45.0B
securitySolution	20.7MB	20.7MB	+15.0B
slo	914.3KB	914.3KB	+15.0B
unifiedHistogram	67.2KB	67.2KB	+15.0B
total			+150.0B

History

• 💔 Build #227102 failed 0e5047e
• 💛 Build #226304 was flaky 03c4aee
• 💔 Build #226184 failed 0984f54

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

cc @ryankeairns

[eokoneyo]

Tested locally, changes look good!