Update message_generated.h to match flatbuffers schema

[maxhgerlach]

Checklist before submitting

• Did you read the contributor guide?
• Did you update the docs?
• Did you write any tests to validate this change?
• Did you update the CHANGELOG, if this change affects users?

Description

Here I've just run flatc on horovod/common/wire/message_generated.fbs. The generated header file was out of sync regarding one of the ReduceOp enum names (as pointed out in #3812).

Review process to land

1. All tests and other checks must succeed.
2. At least one member of the technical steering committee must review and approve.
3. If any member of the technical steering committee requests changes, they must be addressed.

[romerojosh]

Oof, nice catch. That seems to have been due to a last minute commit from my PR that added the new ops where I changed the op name from Prod to Product. Seems the flatbuffers implementation doesn't care about this, since the ordering (and index assignment) is consistent. Good to make consistent anyway!

[github-actions]

Unit Test Results

  1 155 files  ±0    1 155 suites  ±0   13h 9m 40s ⏱️ + 17m 0s
     841 tests ±0       788 ✔️ ±0       53 💤 ±0  0 ❌ ±0 
23 809 runs  ±0  17 023 ✔️ ±0  6 786 💤 ±0  0 ❌ ±0 

Results for commit dcd4423. ± Comparison against base commit bfe96f8.

[github-actions]

Unit Test Results (with flaky tests)

  1 305 files  +  10    1 305 suites  +10   13h 43m 47s ⏱️ + 12m 46s
     841 tests ±    0       788 ✔️ +  1       53 💤 ±    0  0 ❌  - 1 
27 083 runs  +314  18 919 ✔️ +18  8 164 💤 +298  0 ❌  - 2 

Results for commit dcd4423. ± Comparison against base commit bfe96f8.

[EnricoMi]

LGTM!