[BUG] Discover routing without query params does not route correctly

[ashwin-pc]

Describe the bug

Wen visiting the single document or context pages, if the url does not contain query parameters, the routing breaks. e.g.

# Works
http://localhost:5601/app/discover#/context/90943e30-9a47-11e8-b64d-95841ca0b247/oyj5iIwBAXmWFklaNiuy?

# Does not work
http://localhost:5601/app/discover#/context/90943e30-9a47-11e8-b64d-95841ca0b247/oyj5iIwBAXmWFklaNiuy

The issue is with how discover maps the legacy URL's to the new data explorer route. The url parameters after the ? are optional, but the regex currently requires the ? to be present to route the URL correctly.

To Reproduce
Steps to reproduce the behavior:

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior

Routes http://localhost:5601/app/discover#/context/<doc-id>/<index-id> correctly

OpenSearch Version
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Dashboards Version
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Plugins

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Screenshots

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Host/Environment (please complete the following information):

• OS: [e.g. iOS]
• Browser and version [e.g. 22]

Additional context

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[ananzh]

close this since it is fixed in 2.12