Replace GetComputationClientOrDie() with GetComputationClient() (part 2).

[ysiraichi]

This PR replaces calls of the deprecated function GetComputationClientOrDie() with calls to the GetComputationClient() function. The difference between them is that the former throws an exception on error, while the latter returns an status object.

Key Changes:

• Remove GetComputationClientOrDie() function

In general, this PR applies the following replacement pattern:

• Create a new ComputationClient* variable using XLA_ASSIGN_OR_THROW() macro
• Replaces all GetComputationClientOrDie() with the new variable

/* Before */
runtime::ComputationClient::ComputationPtr computation =
    runtime::GetComputationClientOrDie()->DeserializeComputation(
    serialization);

/* After */
XLA_ASSIGN_OR_THROW(runtime::ComputationClient * absl_nonnull client,
                    runtime::GetComputationClient());
runtime::ComputationClient::ComputationPtr computation =
    client->DeserializeComputation(serialization);

Note: this is the part 2 out of 2 PRs. Together, they will phase out GetComputationClientOrDie() function

[zhanyong-wan]

Thanks!