[Explore] remove data-explorer and introduce sample route for flavors

[joshuali925]

Description

This PR removes view service and data-explorer in explore plugin to flatten the structure. It removes registration and management of multiple slices in data-explorer and only uses a single slice, but does not modify the structure. @ananzh I think we'd need to sync up on the state management refactor part.

To introduce a new flavor, the application.tsx component should properly route it to the right page. Example:

              <Route path={[`/logs`]} exact={false}>
                <LogsPage params={params} />
              </Route>
              <Route path={[`/traces`]} exact={false}>
                <TracesPage params={params} />
              </Route>

If user goes to app/explore or app/explore/logs#/, Explore shows the logs flavor. If they go to app/explore/traces#/, it shows the traces flavor. The left nav bar will only show the "Discover" item. Redirection from saved explore is not implemented as they do not store flavor yet.

This PR is built on top of #9813.

Issues Resolved

Screenshot

Testing the changes

Changelog

• refactor: [Explore] remove data-explorer and introduce sample route for flavors

Check List

• All tests pass
  • yarn test:jest
  • yarn test:jest_integration
• New functionality includes testing.
• New functionality has been documented.
• Update CHANGELOG.md
• Commits are signed per the DCO using --signoff

[codecov]

Codecov Report

Attention: Patch coverage is 60.27397% with 29 lines in your changes missing coverage. Please review.

Project coverage is 61.73%. Comparing base (b77db83) to head (b580825).
Report is 26 commits behind head on main.

Files with missing lines	Patch %	Lines
...gins/explore/public/application/logs/logs_page.tsx	66.66%	5 Missing and 4 partials ⚠️
.../explore/public/application/traces/traces_page.tsx	66.66%	5 Missing and 4 partials ⚠️
src/plugins/explore/public/plugin.ts	0.00%	4 Missing ⚠️
...s/explore/public/utils/state_management/preload.ts	55.55%	2 Missing and 2 partials ⚠️
...ins/explore/public/utils/state_management/store.ts	25.00%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #9835   +/-   ##
=======================================
  Coverage   61.73%   61.73%           
=======================================
  Files        3991     3988    -3     
  Lines       95339    95317   -22     
  Branches    15408    15407    -1     
=======================================
- Hits        58858    58848   -10     
+ Misses      32602    32584   -18     
- Partials     3879     3885    +6     

Flag	Coverage Δ
Linux_1	28.82% <ø> (+<0.01%)	⬆️
Linux_2	56.47% <ø> (ø)
Linux_3	39.51% <ø> (ø)
Linux_4	30.07% <60.27%> (-0.02%)	⬇️
Windows_1	28.83% <ø> (+<0.01%)	⬆️
Windows_2	56.43% <ø> (ø)
Windows_3	39.52% <ø> (ø)
Windows_4	30.07% <60.27%> (-0.02%)	⬇️

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[joshuali925]

closing, #9902 will take over