Fix docker restapi start issue, undefined error

[prsunny]

- Why I did it

1. Fix the error during restapi start

Apr 24 01:10:  str-01 INFO restapi.sh: docker: network "host" is specified multiple times.

2. Fix a jinja exception undefined error

Apr 24 01:25: str-01 INFO restapi#: Traceback (most recent call last):
Apr 24 01:25: str-01 INFO restapi#: File "/usr/local/bin/sonic-cfggen", line 318, in <module>
Apr 24 01:25: str-01 INFO restapi#: main()
Apr 24 01:25: str-01 INFO restapi#: return obj[argument]
Apr 24 01:25: str-01 INFO restapi#: jinja2.exceptions.UndefinedError: 'RESTAPI' is undefined

- How I did it
Code fix

- How to verify it
Run restapi docker

- A picture of a cute animal (not mandatory but encouraged)

[prsunny]

retest vsimage please