Make receive calls to redis conn thread safe (#1641)

* Make receive calls to redis conn thread safe

Also removes REDIS_TEST env var. Redis is lightweight and fast, no need
to skip these tests.

* No need to increase the wait

docs/3-Contributing/2-Testing.md

@@ -34,7 +34,7 @@ Check out [the instructions in the `/tools/osquery` directory](../../tools/osque
 To execute the basic unit and integration tests, run the following from the root of the repository:
 
 ```
-MYSQL_TEST=1 REDIS_TEST=1 make test
+MYSQL_TEST=1 make test
 ```
 
 It is a good idea to run `make test` before submitting a Pull Request.
@@ -91,14 +91,6 @@ To run MySQL integration tests set environment variables as follows:
 MYSQL_TEST=1 make test-go
 ```
 
-#### Redis tests
-
-To run Redis integration tests set environment variables as follows:
-
-```
-REDIS_TEST=1 make test-go
-```
-
 #### Email tests
 
 To run email related integration tests using MailHog set environment as follows: