Search for ports sequentially instead of at random for more predictable port selection

[mvines]

solana-validator currently randomly selects UDP/TCP ports within its port range at startup, which makes traffic analysis harder than it should be. Instead sequentially walk the port range for the first open port so allocations are deterministic (assuming no port conflicts).

Fixes #9399
cc: @leoluk

[leoluk]

Cool, cherry-picked on tds (on top of v1.1.2), works great and is stable between restarts:

 |Gossip| TPU  |TPUfwd| TVU  |TVUfwd|Repair|ServeR|Storag| RPC  |PubSub|ShredVer
-+------+------+------+------+------+------+------+------+------+------+--------
 | 8000 | 8003 | 8004 | 8001 | 8002 | 8006 | 8007 | none | none | none | 18216

[codecov]

Codecov Report

Merging #9411 into master will decrease coverage by 0.0%.
The diff coverage is 100.0%.

@@           Coverage Diff            @@
##           master   #9411     +/-   ##
========================================
- Coverage    81.1%   81.1%   -0.1%     
========================================
  Files         277     277             
  Lines       62227   62209     -18     
========================================
- Hits        50512   50494     -18     
  Misses      11715   11715             

[mvines]

nice, this PR scared out some crappy tests 🛠️

[sakridge]

lgtm