LSF driver resource string can fail with host exclusion

[berland]

If rusage and select are already present in the LSF resource string, and a user supplies a list of hosts to exlude, the LSF driver will build an invalid string.

This easily happens as both these are typically set through ert-configurations.

The existing parametrized test can be augmented to make this fail:

        pytest.param(
            "select[location=='cloud'] rusage[mem=7000]",
            ["rogue_host"],
            "select[location=='cloud' && hname!='rogue_host'] rusage[mem=7000]",
            id="select_and_rusage_in_resource_requirement_one_excluded_hosts",
        ),

    def test_build_resource_requirement_string(
        resource_requirement: Optional[str], exclude_hosts: List[str], expected_string: str
    ):
>       assert (
            build_resource_requirement_string(exclude_hosts, resource_requirement)
            == expected_string
        )
E       assert "select[locat...'rogue_host']" == 'select[locat...age[mem=7000]'
E         
E         - select[location=='cloud' && hname!='rogue_host'] rusage[mem=7000]
E         + select[location=='cloud'] rusage[mem=7000 && hname!='rogue_host']

tests/unit_tests/scheduler/test_lsf_driver.py:650: AssertionError

[berland]

The bug is due do rindex("]") which locates the wrong end of the select clause.

https://github.com/equinor/ert/blob/2ce20800e12006202828c3e7e657c13fb96e0c6f/src/ert/scheduler/lsf_driver.py#L150