Prop275: When 0.2.9 is the oldest remaining supported series, make 'published' times uniform
In #21642 (moved), we did the necessary preliminary work to make sure that Tor 0.2.9.x and later could behave themselves when the 'published' date in every consensus document was sent to the future.
When older series are all unsupported, we can finish proposal 275, and set 'published' to e.g. 2038-01-01 00:00:00 in every "r" line in every consensus document.
This change will make consensus diffs much, much smaller.
Leaving in 0.3.2, though 0.3.4 or 0.3.5 seems likelier.