[MultiDB]:sonic-swss replace old API with new APIs

[Pan-XT]

What I did Replace DBConnector old APIs with new APIs Why I did it Enable Multi DB

I implemented similar changes in https://github.com/sonic-net/sonic-swss/pull/1138

[linux-foundation-easycla[bot]]

The committers listed above are authorized under a signed CLA.

• :white_check_mark: login: Pan-XT / name: PanXuntao (d1d8ab00aafd9ff9e54e7de29ef40a4c4cd4d812, 0b39af706f41daaa618f470efafdadaff619b044)

[eddieruan-alibaba]

Cherry picked to Phoenix wing

https://github.com/eddieruan-alibaba/sonic-swss/commit/c0654183f11c10422725aed9302de9f911cdc756

[eddieruan-alibaba]

Verified in Phoenix wing's daily sanity.

http://phoenixwing.com.cn/vsonic

[eddieruan-alibaba]

Validated with phoenix wing

admin@PE3:~$ ls -l /etc/sonic/enable_multidb -rw-r--r-- 1 root root 0 Oct 11 01:46 /etc/sonic/enable_multidb admin@PE3:~$ ps aux | grep redis message+ 990 0.8 0.5 86764 39228 pts/0 Sl 06:28 7:06 /usr/bin/redis-server 127.0.0.1:6379 message+ 991 0.8 0.2 71404 21248 pts/0 Rl 06:28 6:50 /usr/bin/redis-server 127.0.0.1:6380 message+ 992 0.3 0.2 64748 17384 pts/0 Sl 06:28 2:28 /usr/bin/redis-server 127.0.0.1:6381 message+ 994 2.9 0.3 71404 24000 pts/0 Sl 06:28 23:44 /usr/bin/redis-server 127.0.0.1:6382 message+ 996 0.1 0.2 62188 16904 pts/0 Sl 06:28 1:22 /usr/bin/redis-server 127.0.0.1:6383

This PR is a minor fix to update some old api to use new api.