KNOX-2774 - "usage: sleep seconds" messages in terminal after starting knox

[MrtnBalazs]

What changes were proposed in this pull request?

Changed the value of DEFAULT_APP_STATUS_TEST_RETRY_SLEEP from 2s to 2 in knox-functions.sh, because sleep command in BSD family of operating systems (such as FreeBSD) or macOS/mac OS X does NOT take any suffix arguments (m/h/d). It only takes arguments in seconds.

How was this patch tested?

I tested it manually.
Before the change:

mbalazs-MBP15:test mbalazs$ bin/gateway.sh start
usage: sleep seconds
usage: sleep seconds
.
.
.
usage: sleep seconds
usage: sleep seconds
Starting Gateway succeeded with PID 55659.

After the change:

mbalazs-MBP15:test mbalazs$ bin/gateway.sh start
Starting Gateway succeeded with PID 55659.

I also tried a request using curl -k -u tom:tom-password https://localhost:8443/gateway/sandbox/hive and got

2022-07-07 14:50:25,037 726f3103-8de2-4ff8-9bc8-f47f8929da49 INFO  knox.gateway (KnoxLdapRealm.java:getUserDn(688)) - Computed userDn: uid=tom,ou=people,dc=hadoop,dc=apache,dc=org using dnTemplate for principal: tom

[MrtnBalazs]

@zeroflag @smolnar82

[smolnar82]

LGTM