Motivation:
From the recent benchmark using gRPC-Java based on Netty's HTTP2, it appears that it prefers `ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256` over `ECDHE_ECDSA_WITH_AES_128_GCM_SHA256` since it uses the Netty HTTPS Cipher list as is. Both are considered safe but `ECDHE_ECDSA_WITH_AES_128_GCM_SHA256` has a good chance to get more optimized implementation. (e.g. AES-NI) When running both on GCP Intel Haswell VM, `TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256` spent 3x CPU time than `TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256`. (Note that this VM supports AES-NI)
From the cipher suites listed on `Intermediate compatibility (recommended)` of [Security/Server Side TLS](https://wiki.mozilla.org/Security/Server_Side_TLS#Modern_compatibility), they have a cipher preference which is aligned with this PR.
```
0x13,0x01 - TLS_AES_128_GCM_SHA256 TLSv1.3 Kx=any Au=any Enc=AESGCM(128) Mac=AEAD
0x13,0x02 - TLS_AES_256_GCM_SHA384 TLSv1.3 Kx=any Au=any Enc=AESGCM(256) Mac=AEAD
0x13,0x03 - TLS_CHACHA20_POLY1305_SHA256 TLSv1.3 Kx=any Au=any Enc=CHACHA20/POLY1305(256) Mac=AEAD
0xC0,0x2B - ECDHE-ECDSA-AES128-GCM-SHA256 TLSv1.2 Kx=ECDH Au=ECDSA Enc=AESGCM(128) Mac=AEAD
0xC0,0x2F - ECDHE-RSA-AES128-GCM-SHA256 TLSv1.2 Kx=ECDH Au=RSA Enc=AESGCM(128) Mac=AEAD
0xC0,0x2C - ECDHE-ECDSA-AES256-GCM-SHA384 TLSv1.2 Kx=ECDH Au=ECDSA Enc=AESGCM(256) Mac=AEAD
0xC0,0x30 - ECDHE-RSA-AES256-GCM-SHA384 TLSv1.2 Kx=ECDH Au=RSA Enc=AESGCM(256) Mac=AEAD
0xCC,0xA9 - ECDHE-ECDSA-CHACHA20-POLY1305 TLSv1.2 Kx=ECDH Au=ECDSA Enc=CHACHA20/POLY1305(256) Mac=AEAD
0xCC,0xA8 - ECDHE-RSA-CHACHA20-POLY1305 TLSv1.2 Kx=ECDH Au=RSA Enc=CHACHA20/POLY1305(256) Mac=AEAD
0x00,0x9E - DHE-RSA-AES128-GCM-SHA256 TLSv1.2 Kx=DH Au=RSA Enc=AESGCM(128) Mac=AEAD
0x00,0x9F - DHE-RSA-AES256-GCM-SHA384 TLSv1.2 Kx=DH Au=RSA Enc=AESGCM(256) Mac=AEAD
```
Modification:
Moving up `AES_128_GCM_SHA256` in the CIPHERS of HTTPS so that it gets priority.
Result:
When connecting to the server supporting both `ECDHE_ECDSA_WITH_AES_128_GCM_SHA256` and `ECDSA_WITH_CHACHA20_POLY1305_SHA256` and respecting the client priority of cipher suites, it will be able to save significant cpu time when running it on machines with AES-NI support.
573ff0a33e