Bug 964880 - Add swap to linux build machines with <12GB RAM. r=rail

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extra : amend_source : 4bd421b17a9a9ee0c7ddfd115a909fdf5eb5b299
Bug 966070 - s/m1.large/m3.medium/ r=rail
Bug 977187: drop one of two anyjson lines for selfserve-agent; r=bhearsum
bug 977824: give larsberg access to servo machines. r=dustin
Merge bugs 964880, 966070, 977187, and 977824 to production.

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branch : production