crypto/tls: re-enable two TLS tests with fips140tls.Required

[cpu]

Two small TODOs that came out of CR 629736:

1. In handshake_server_test.go the "RSA" and "RSA with ec_point_format" subtests of TestTLSPointFormats are skipped when fips140tls.Requried() is enabled, otherwise a handshake failure error is observed. This should be debugged (I suspect I'm overlooking someting small) and the subtests re-enabled for FIPS TLS mode.

2. The TestRenegotiationExtension test is skipped when fips140tls.Required() is enabled due to its use of RC4 ciphersuites and the RSA 1024 test certificate hiearchy. This should be possible to enable in FIPS TLS mode by replacing RC4 with an AES ciphersuite and using RSA 2048 test certs. Doing so was giving a "Server returned short message of length 7" error. This should be debugged and the test re-enabled for FIPS TLS mode.

[gabyhelp]

Related Code Changes

• crypto/tls: test with FIPS 140-3 TLS mode

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