[BUG] `salt-call` grains module doesn't have access to pillar

Description
What's particularly weird about this issue is that salt-call does have access to pillar when running salt-call saltutil.sync_grains and/or saltutil.refresh_grains but doesn't when retrieiving the grain, e.g. salt-call grains.item or salt-call grains.get. Using pillar in the __virtual__ function as shown below, this results in not being able to retrieve the custom grain with salt-call.

Setup

Install salt-master and salt-minion on a VM. Configure with the following files.

# /etc/salt/master.d/master.conf
user: root

# /etc/salt/minion.d/minion.conf
master: localhost
log_level_logfile: info

# /srv/salt/_grains/test_grain.py
import logging

log = logging.getLogger(__name__)

__virtualname__ = "test_grain"

def __virtual__():
    if __pillar__.get("test"):
        log.info("has test pillar")
        return __virtualname__
    log.info("doesn't have test pillar")
    return (False, "doesn't have test pillar set to True")

def test_grain():
    log.info("test_grain")
    return {"test_grain": "abc123"}

# /srv/pillar/top.sls
base:
  "*":
    - test

# /srv/pillar/test.sls
test: True

Restart the minion and master, as necessary, and accept the minion key. Refresh pillar and sync_grains, as necessary.

Steps to Reproduce the behavior

After syncing grains via saltutil.sync_grains observe that you are able to retrieve the grain with

salt \* grains.item test_grain

but not with

salt-call grains.item test_grain

From the log statements included in the module, we can see in the logs that the pillar is not available when using salt-call grains.item, but is when calling salt-call saltutil.sync_grains (but looks like it's evaluated twice in the latter case and maybe why??)

Expected behavior
salt-call should behave the same as with the salt command in its ability to retrieve custom grains even when pillar is used in __virtual__

Versions Report

Salt Version:
          Salt: 3007.0
 
Python Version:
        Python: 3.10.13 (main, Feb 19 2024, 03:31:20) [GCC 11.2.0]
 
Dependency Versions:
          cffi: 1.16.0
      cherrypy: 18.8.0
      dateutil: 2.8.2
     docker-py: Not Installed
         gitdb: Not Installed
     gitpython: Not Installed
        Jinja2: 3.1.3
       libgit2: Not Installed
  looseversion: 1.3.0
      M2Crypto: Not Installed
          Mako: Not Installed
       msgpack: 1.0.7
  msgpack-pure: Not Installed
  mysql-python: Not Installed
     packaging: 23.1
     pycparser: 2.21
      pycrypto: Not Installed
  pycryptodome: 3.19.1
        pygit2: Not Installed
  python-gnupg: 0.5.2
        PyYAML: 6.0.1
         PyZMQ: 25.1.2
        relenv: 0.15.1
         smmap: Not Installed
       timelib: 0.3.0
       Tornado: 6.3.3
           ZMQ: 4.3.4
 
Salt Package Information:
  Package Type: onedir
 
System Versions:
          dist: ubuntu 22.04.2 jammy
        locale: utf-8
       machine: x86_64
       release: 5.15.0-67-generic
        system: Linux
       version: Ubuntu 22.04.2 jammy

Reproduce the behavior with the provided master/minion configuration and /srv/salt/_grains/test_grain.py, comparing salt * grains.item test_grain with salt-call grains.item test_grain. Trace the salt-call grains and saltutil.sync_grains or saltutil.refresh_grains entry points; done means salt-call can retrieve the custom grain when virtual uses pillar.