Remove obsolete prefs from meek-http-helper-user.js

I was looking at the HTTP helper and I noticed that we no longer need to override the network.http.spdy.* prefs.

I did a testbuild with this patch on top of 50193b4aff592e79b5a45fccb2a1547cef8e2691, tried meek-azure, and got fingerprint bb94e801f7aee52b as before (as in legacy/trac#26241 (moved))

added TorBrowserTeam201902R in Legacy / Trac component::applications/tor browser in Legacy / Trac meek in Legacy / Trac owner::tbb-team in Legacy / Trac priority::medium in Legacy / Trac resolution::fixed in Legacy / Trac severity::normal in Legacy / Trac status::closed in Legacy / Trac type::enhancement in Legacy / Trac labels

Trac:
0001-Bug-29349-Remove-network.http.spdy.-overrides-from-m.patch

Trac:
Status: new to needs_review

Looks good to me, thanks! Applied to master (commit 9117e69a41563c21621d7337357d9da7c8958573).

Trac:
Status: needs_review to closed
Resolution: N/A to fixed
Keywords: N/A deleted, TorBrowserTeam201902R added

closed

moved from legacy/trac#29349 (moved)

added Feature label and removed 1 deleted label

removed 1 deleted label