Remove Roboto Font to Improve Performance and Consistency

### What is this about?

This task involves the removal of the Roboto font from MetaMask mobile. Currently, Roboto is being used as a fallback font, but it is mostly unnecessary since Euclid Circular B is the primary font. The investigation has revealed that Roboto is only utilized in a few select instances and could likely be removed entirely to streamline the font loading process and improve performance.

### Scenario

_No response_

### Design

_No response_

### Technical Details

- Audit the mobile to confirm all instances of Roboto usage.
- Replace Roboto with Euclid Circular B where necessary.
- If Euclid is unavailable, configure the font stack to fall back to system fonts rather than another custom font.

### Threat Modeling Framework

_No response_

### Acceptance Criteria

- Roboto should be completely removed from the MetaMask mobiles's CSS and other relevant files.
- The font stack should fall back to system fonts when Euclid Circular B is unavailable.
- Verify that the removal does not negatively impact the UI/UX.
- Test to confirm no regression or issues arise from this change.

### Stakeholder review needed before the work gets merged

- [X] Engineering (needed in most cases)
- [ ] Design
- [ ] Product
- [ ] QA (automation tests are required to pass before merging PRs but not all changes are covered by automation tests - please review if QA is needed beyond automation tests)
- [ ] Security
- [ ] Legal
- [ ] Marketing
- [ ] Management (please specify)
- [ ] Other (please specify)

### References

- [Slack thread](https://consensys.slack.com/archives/CTQAGKY5V/p1724173426966159)

Start by auditing MetaMask mobile's CSS and other relevant files for every Roboto reference, then identify the few usages described in the issue. Replace those usages with Euclid Circular B or system-font fallbacks, and verify that Roboto is absent and no UI regressions appear in testing.

Written by the indexing model from the issue text.