MTL-1925 Fix metal.ipv4

[rustydb]

Summary and Scope

• Fixes: MTL-1925

Issue Type

• Bugfix Pull Request

When metal.ipv4 was set to 1 it was ignored by ping and curl calls. This change restores the functionality.

Simple example showing how it works, why 0 is changed to '' and why 1 allows the substitution.

ncn-w004:~ # [ "${metal_ipv4}" = 0 ] && metal_ipv4=''
+ '[' 0 = 0 ']'
+ metal_ipv4=
ncn-w004:~ # ping ${metal_ipv4:+-4} ncn-w004
+ ping ncn-w004
PING ncn-w004(surtur-ncn-w004.local (::1)) 56 data bytes
64 bytes from surtur-ncn-w004.local (::1): icmp_seq=1 ttl=64 time=0.044 ms
^C
--- ncn-w004 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.044/0.044/0.044/0.000 ms
ncn-w004:~ # ^C
ncn-w004:~ # metal_ipv4=1
+ metal_ipv4=1
ncn-w004:~ # [ "${metal_ipv4}" = 0 ] && metal_ipv4=''
+ '[' 1 = 0 ']'
ncn-w004:~ # ping ${metal_ipv4:+-4} ncn-w004
+ ping -4 ncn-w004

Prerequisites

• I have included documentation in my PR (or it is not required)
• I tested this on internal system (if yes, please include results or a description of the test)
• I tested this on a vshasta system (if yes, please include results or a description of the test)

Idempotency

Risks and Mitigations