Revert of Disable spdy tests for constant failures on Volantis bot (patchset...

Revert of Disable spdy tests for constant failures on Volantis bot (patchset #2 id:20001 of https://codereview.chromium.org/836033006/)

Reason for revert:
https://crrev.com/852053002 fixes the tests, they can be re-enabled.

Original issue's description:
> Disable spdy tests for constant failures on Volantis bot
>
> Per
> https://uberchromegw.corp.google.com/i/clank/builders/instrumentation-volantis-clankium-lmp,
> all spdy related tests have failed on volantis bot.
>
> BUG=447837
>
> Committed: https://crrev.com/f13f7dbe2ec8d008d7aefa4c625d297685e62435
> Cr-Commit-Position: refs/heads/master@{#311401}

BUG=447837

Review URL: https://codereview.chromium.org/800613008

Cr-Commit-Position: refs/heads/master@{#311555}

build/android/pylib/gtest/filter/net_unittests_disabled

@@ -45,7 +45,3 @@ HttpCache.TypicalGET_ConditionalRequest
 # These are death tests and thus also disabled.
 PrioritizedDispatcherTest.CancelNull
 PrioritizedDispatcherTest.CancelMissing
-
-# http://crbug.com/447837
-Spdy/SpdyNetworkTransactionTest.HTTP11RequiredRetry/4
-Spdy/SpdyNetworkTransactionTest.HTTP11RequiredRetry/7
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