[MacPorts] #56017: Buildbot: Replace WithProperties with Interpolate

[MacPorts]

#56017: Buildbot: Replace WithProperties with Interpolate
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  Reporter:  ryandesign     |      Owner:  admin@…
      Type:  enhancement    |     Status:  new
  Priority:  Normal         |  Milestone:
 Component:  buildbot/mpbb  |    Version:
Resolution:                 |   Keywords:
      Port:                 |
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Comment (by ryandesign):

 I'm doing this as I convert the config over to [ticket:56044 buildbot 2].

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Ticket URL: <https://trac.macports.org/ticket/56017#comment:1>
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