Use `sentry-cli sourcemaps upload` instead of legacy command

[szokeasaurusrex]

DESCRIBE YOUR PR

This change removes all references to the legacy sentry-cli releases files upload-sourcemaps command, and replaces then with references to sentry-cli sourcemaps upload, the new command.

Resolves #10270

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[szokeasaurusrex]

Mobile-team-relevant changes in 676f35ded8151adf78a664aac08f635251e6ac35 Frontend-team-relevant changes in b9e3fd5197220c9a922d591d780ec99c19672c61

[codecov[bot]]

Bundle Report

Changes will decrease total bundle size by 15 bytes :arrow_down:

Bundle name	Size	Change
sentry-docs-edge-server	250.13kB	3 bytes :arrow_down:
sentry-docs-server	8.29MB	6 bytes :arrow_down:
sentry-docs-client	7.87MB	6 bytes :arrow_down:

[philipphofmann]

Mobile-team-relevant changes in https://github.com/getsentry/sentry-docs/commit/676f35ded8151adf78a664aac08f635251e6ac35

This only affects React-Native, so I leave this to @krystofwoldrich.

[szokeasaurusrex]

@loewenheim, could I get a review from you here?