SETs named `testcases:metric_context_path:<testcase name>` is not being properly set

[filipecosta90]

Issue: keyname is not being properly set. we should see ...testcases:metric_context_path:<testcase name> and we're seeing testcases:metric_context_path:None

benchmarks.redislabs.com:12011> "smembers" "ci.benchmarks.redislabs/ci/redis/redis:testcases:metric_context_path:redis-benchmark-full-suite-1Mkeys-100B"
(empty array)
benchmarks.redislabs.com:12011> "smembers" "ci.benchmarks.redislabs/ci/redis/redis:testcases:metric_context_path:None"
 1) "LRANGE_300"
 2) "SADD"
 3) "GET"
 4) "RPUSH"
 5) "INCR"
 6) "LRANGE_600"
 7) "LPOP"
 8) "SPOP"
 9) "HSET"
10) "ZADD"
11) "ZPOPMIN"
12) "LRANGE_500"
13) "RPOP"
14) "PING_INLINE"
15) "MSET"
16) "SET"
17) "LRANGE_100"
18) "PING_MBULK"
19) "LPUSH"