message: Make bitwise convert inplace read only
  Summary:
  It doesn't actually modify the value.
  ref T30072
  Test Plan: CI
  Reviewers: jakeh, #tensorflow, #framework_ip_review_-_any_oss_or_third-party_code_use_has_been_approved, jackh
  Maniphest Tasks: T30072
diff: @@ -381,7 +381,6 @@ HloInstructionDescription::HloInstructionDescription(
  // Inplace read/write ops.
  // Unary Elementwise ops - inplace on operand 0.
  case HloOpcode::kAbs:
  - case HloOpcode::kBitcastConvert:
  case HloOpcode::kCeil:
  case HloOpcode::kClz:
  case HloOpcode::kCos:
  @@ -587,6 +586,7 @@ HloInstructionDescription::HloInstructionDescription(
  // Inplace read-only ops.
  // These ops are implemented as inplace ops on operand 0.
  case HloOpcode::kAddDependency:
  + case HloOpcode::kBitcastConvert:
  case HloOpcode::kBroadcast:
  case HloOpcode::kReshape:
  case HloOpcode::kReverse:
  