Fix NaN issue in Product Tour Popover

[vthomas13]

Description

The Popover is displaying NaN because the '/' was not being treated as a string.
Fixed that and added a test to help prevent it in the future.

Related issues

Fixes: https://github.com/MetaMask/metamask-extension/pull/22905/files#r1498090474

Manual testing steps

1. Fresh install of metamask, open popup
2. Verify that the product tour popover starts by displaying 1/3
3. run tests with yarn jest ui/components/multichain/product-tour-popover/product-tour-popover.test.js
4. Verify new test passes 'should render correct steps' or fails under the right circumstances

Screenshots/Recordings

Before

After

Pre-merge author checklist

• I’ve followed MetaMask Coding Standards.
• I've clearly explained what problem this PR is solving and how it is solved.
• I've linked related issues
• I've included manual testing steps
• I've included screenshots/recordings if applicable
• I’ve included tests if applicable
• I’ve documented my code using JSDoc format if applicable
• I’ve applied the right labels on the PR (see labeling guidelines). Not required for external contributors.
• I’ve properly set the pull request status:
  • In case it's not yet "ready for review", I've set it to "draft".
  • In case it's "ready for review", I've changed it from "draft" to "non-draft".

Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[metamaskbot]

Builds ready [916cfda]

• builds: chrome, firefox
• builds (beta): chrome
• builds (flask): chrome, firefox
• builds (MMI): chrome, firefox
• builds (test): chrome, firefox
• builds (test-flask): chrome, firefox
• build viz: Build System
• mv3: Background Module Init Stats
• mv3: UI Init Stats
• mv3: Module Load Stats
• mv3: Bundle Size Stats
• mv2: E2e Actions Stats
• code coverage: Report
• storybook: Storybook
• typescript migration: Dashboard
• all artifacts
• bundle viz:

  • background: 0, 1, 2, 3, 4, 5
  • common: 0, 1, 2, 3, 4, 5, 6
  • content-script: 0
  • contentscript: contentscript
  • disable-console: disable-console
  • policy-load: policy-load
  • sentry-install: sentry-install
  • ui: 0, 1, 10, 11, 2, 3, 4, 5, 6, 7, 8, 9

Page Load Metrics (1925 ± 99 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	115	475	215	89	43
		domContentLoaded	13	85	36	21	10
		load	1555	2442	1925	206	99
		domInteractive	13	85	36	21	10

Bundle size diffs

• background: 0 Bytes (0.00%)
• ui: 49 Bytes (0.00%)
• common: 0 Bytes (0.00%)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (afb1b66) 68.49% compared to head (916cfda) 68.49%.
Report is 2 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop   #23100   +/-   ##
========================================
  Coverage    68.49%   68.49%           
========================================
  Files         1090     1090           
  Lines        43133    43133           
  Branches     11501    11501           
========================================
  Hits         29541    29541           
  Misses       13592    13592           

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