[fix]: Chunked cloud firewall rules of only 1 addr type result in empty rule and failed updates

[wbh1]

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Description

tl;dr — if you have a large firewall that exceeds the 255 address limit and kicks in the chunking logic, if that large firewall rule contains only 1 address type (i.e. all IPv4 or all IPv6) then the CCM still tries to add an empty rule for the address type.

This does the dumb, simple thing of just checking the length of the rules for each addr type before chunking them.

Example with a big rule of only IPv4 addrs:

 I0831 16:54:33.298782   37901 firewalls.go:305] Firewall label 'ACCEPT-platform-components-gateway-istio' is too long. Stripping to
 'ACCEPT-platform-components-gatew'
 inbound rules: 3
 rule 0: IPv4=255 IPv6=0
 rule 1: IPv4=9 IPv6=0
 rule 2: IPv4=0 IPv6=0

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.91%. Comparing base (602a9e1) to head (615d382).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #620      +/-   ##
==========================================
+ Coverage   75.89%   75.91%   +0.01%     
==========================================
  Files          18       18              
  Lines        2809     2811       +2     
==========================================
+ Hits         2132     2134       +2     
  Misses        464      464              
  Partials      213      213              

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[AshleyDumaine]

This does the dumb, simple thing of just checking the length of the rules for each addr type before chunking them.

While this change works, I'm thinking we'll want to fix chunkIPs to actually return nil if the length of the ips is zero instead of just adding the checks here. WDYT?

[wbh1]

While this change works, I'm thinking we'll want to fix chunkIPs to actually return nil if the length of the ips is zero instead of just adding the checks here. WDYT?

Good point — I switched the approach so that chunkIPs will return nil when called using an empty slice as the arg to the function.