Revert "[lldb/Target] Delay image loading after corefile process creation (#70351)"

This reverts commit 3c727a95 because it
introduced some test failures:

https://lab.llvm.org/buildbot/#/builders/68/builds/62638



```
********************
Failed Tests (5):
  lldb-api :: functionalities/postmortem/elf-core/TestLinuxCore.py
  lldb-api :: functionalities/postmortem/mach-core/TestMachCore.py
  lldb-api :: functionalities/postmortem/netbsd-core/TestNetBSDCore.py
  lldb-api :: functionalities/unwind/noreturn/module-end/TestNoReturnModuleEnd.py
  lldb-api :: tools/lldb-dap/coreFile/TestDAP_coreFile.py
```

Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>