Fix assert failure triggered by "CREATE INDEX CONCURRENTLY"

[fairyfar]

What does this PR do?

When resource groups are enabled, StartTransaction() may have taken a catalog snapshot
within GetResGroupIdForRole, and xmin is not InvalidTransactionId. Therefore, it does
not meet the status requirements for "CREATE INDEX CONCURRENTLY".

Reproduction method:

1. Compile Debug version and enable assert.

./configure --enable-debug --enable-cassert

2. Enable resource group management.

gp_resource_manager='group'

3. Test Case

create table t(a text, b text);
-- crash:
create index concurrently t_idx on t(a, b);
-- "ERROR:  relation "t_idx" already exists". Indicates that the transaction has been successfully committed.
create index concurrently t_idx on t(a, b);

4. Test Results

[fairyfar@bogon cloudberry]$ psql postgres
psql (16.9, server 16.9)
Type "help" for help.

postgres=# create table t(a text, b text);
NOTICE:  Table doesn't have 'DISTRIBUTED BY' clause -- Using column named 'a' as the Apache Cloudberry data distribution key for this table.
HINT:  The 'DISTRIBUTED BY' clause determines the distribution of data. Make sure column(s) chosen are the optimal data distribution key to minimize skew.
CREATE TABLE
postgres=# create index concurrently t_idx on t(a, b);
FATAL:  Unexpected internal error (assert.c:46)
DETAIL:  ("MyProc->xid == InvalidTransactionId && MyProc->xmin == InvalidTransactionId", File: "indexcmds.c", Line: 5459)
server closed the connection unexpectedly
        This probably means the server terminated abnormally
        before or while processing the request.
The connection to the server was lost. Attempting reset: Failed.
The connection to the server was lost. Attempting reset: Failed.
!?> \q

[fairyfar@bogon cloudberry]$ psql postgres
psql (16.9, server 16.9)
Type "help" for help.

postgres=# create index concurrently t_idx on t(a, b);
ERROR:  relation "t_idx" already exists

Type of Change

• Bug fix (non-breaking change)
• New feature (non-breaking change)
• Breaking change (fix or feature with breaking changes)
• Documentation update

Breaking Changes

Test Plan

• Unit tests added/updated
• Integration tests added/updated
• Passed make installcheck
• Passed make -C src/test installcheck-cbdb-parallel

Impact

Performance:

User-facing changes:

Dependencies:

Checklist

• Followed contribution guide
• Added/updated documentation
• Reviewed code for security implications
• This PR contains AI-assisted code generation
• Requested review from cloudberry committers

Additional Context

CI Skip Instructions

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[yjhjstz]

Can you add related test create index concurrently t_idx on t(a, b); ?

[fairyfar]

I'm very sorry. The test case of ic-resgroup-v2 failed. It's related to this commit. Let me analyze the reasons.