ProcParts inside a fairing register with a min 1m diameter

[lpgagnon]

Seen with v6.0_RC1 (#fb0326f), don't know how long it's been there

https://discord.com/channels/319857228905447436/620690446540341261/845710042883948574

Place an interstage base with 1 side part, give the base a top & bottom diameter < 1m (say 0.5m). Then place a procparts tank on the base's middle node, and change its diameter.

Expected: with a tank diameter <0.5m, the fairing is a straight cylinder. Tank diameters > 0.5m make the fairing swell out
Actual: fairing diameter swells out to ~1m diameter even with a smaller tank. >1m tanks inflate the fairing as expected

Extra note: the fairing doesn't act as if the full height of the tank is 1m, only its middle(ish) section

[DRVeyl]

The surface attachment collider on the ProcPart is, for whatever reason, always positioned at z=0.5 and in the middle of the part. Presumably this is where it starts on an unmodified ProcPart cylinder. So when PF tries to scan everything and determine what is inside, this is identified as something to be kept within the fairing. Thus the minimum radius is found to be 0.5, and it's "correctly" placed at the center.