Fix the issue with the xDS flow control functionality integration test

[hanbingleixue]

What happened?

1. Added support for Okhttp2 2.2.0.
2. The number of retry times is incorrect because the response header of HttpUrlConnection is not updated.
3. The flow control configuration cannot obtain the millisecond-level time.
4. Some retry conditions are inconsistent with Istio.

How can we reproduce it (as minimally and precisely as possible)?

1. Use Okhttp2 2.2.0 to test the flow control function. The problem can be reproduced.
2. When HttpUrlConnection is used to retry with a specified response header, the response header obtained after the retry is still the first response header, and the retry times are reached.
3. The flow control function does not take effect when the time in the flow control matching configuration is set to ms.
4. Retry conditions for link errors are configured. Retry is performed when the request times out.

Anything else we need to know?

No response

Sermant version

2.2.0

OS version

# On Linux:
$ cat /etc/os-release
# paste output here
$ uname -a
# paste output here

# On Windows:
C:\> wmic os get Caption, Version, BuildNumber, OSArchitecture
# paste output here