Migrate SKIPIF -> EXTENSIONS (#7138)

This is an automated migration of most SKIPIF extension_loaded checks.

Use ServerClientTestCase in a test for default_socket_timeout=-1

Fix test for bug62890 to not depend on system cert store

Fix #62890: default_socket_timeout=-1 causes connection to timeout

While unencrypted connections ignore negative timeouts, SSL/TLS
connections did not special case that, and so always fa

Fix #62890: default_socket_timeout=-1 causes connection to timeout

While unencrypted connections ignore negative timeouts, SSL/TLS
connections did not special case that, and so always failed due to
timeout.

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