Fix race condition in ProcessesSync causing SSH key mismatch

[philippthun]

The sync could update an LRP with stale SSH route data from a previous version when the process version changed between the initial scan and the batch execution.

Timeline of the race condition:

  Sync                              User Request
  ----                              ------------
  |                                      |
  | fetch diego LRPs                     |
  | (gets {guid}-{vA} with SSH key A)    |
  |                                      |
  | scan CC processes                    |
  | process has version A, matches       |
  | to_update[id] = diego_lrp_A          |
  |                                      |
  |                                      | update process
  |                                      | version changes to B
  |                                      |
  |                                      | desire_app called
  |                                      | creates {guid}-{vB}
  |                                      | with new SSH key B
  |                                      |
  | re-fetch process by id               |
  | (now has version B)                  |
  |                                      |
  | update_app(process_vB, diego_lrp_A)  |
  | process_guid = {guid}-{vB}           |
  | but uses SSH route from diego_lrp_A! |
  |                                      |
  v                                      v

Result: LRP {guid}-{vB} has SSH key A in routes but SSH key B in run_info (sshd arguments), breaking cf ssh.

Fix: Before executing desire/update, verify the process version still matches what was recorded during the initial scan. Skip if mismatched - the next sync cycle will handle it correctly.

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