Revert "Make SSLConfigService owned, rather than RefCounted"

This reverts commit 462a4314c79d940a283af9d504602ef55f6aa08b.

Reason for revert: P2PSocketDispatcherHost, which creates a
ProxyResolvingClientSocketFactory from a URLRequestContext,
outlives the URLRequestContext and thus causes shutdown
ordering issues, since it uses URLRequestContext members.

Original change's description:
> Make SSLConfigService owned, rather than RefCounted
> 
> The introduction of SSLConfigServiceMojo finally
> provided the cut point in the SSLConfigService
> interface that allows it to no longer be refcounted,
> and instead fully owned by the URLRequestContextStorage.
> 
> BUG=56213
> [email protected]
> 
> Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;luci.chromium.try:linux_mojo;master.tryserver.chromium.mac:ios-simulator-cronet
> Change-Id: I8833234d08ab8f40e6a3f30859e69ba0552643b2
> Reviewed-on: https://chromium-review.googlesource.com/1123929
> Commit-Queue: Ryan Sleevi <[email protected]>
> Reviewed-by: Richard Coles <[email protected]>
> Reviewed-by: Sylvain Defresne <[email protected]>
> Reviewed-by: Martin Šrámek <[email protected]>
> Reviewed-by: Matt Menke <[email protected]>
> Cr-Commit-Position: refs/heads/master@{#572860}

[email protected],[email protected],[email protected],[email protected],[email protected],[email protected]

Change-Id: I0063814e7b1691ee0d581a2c043aa7431e4dfc6d
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 56213
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;luci.chromium.try:linux_mojo;master.tryserver.chromium.mac:ios-simulator-cronet
Reviewed-on: https://chromium-review.googlesource.com/1128193
Reviewed-by: Ryan Sleevi <[email protected]>
Commit-Queue: Ryan Sleevi <[email protected]>
Cr-Commit-Position: refs/heads/master@{#573084}
54 files changed