How to use the taskgraph.util.treeherder.join_symbol function in taskgraph

Restore the -e10s suffix (because some day we will have them!)

    Reverses the effects of bug 1541527. Thunderbird builds are all single
    process.
    """
    for job in jobs:
        test = job['run']['test']
        e10s = test['e10s']

        if not e10s:  # test-name & friends end with '-1proc'
            test['test-name'] = _remove_suffix(test['test-name'], '-1proc')
            test['try-name'] = _remove_suffix(test['try-name'], '-1proc')
            group, symbol = split_symbol(test['treeherder-symbol'])
            if group != '?':
                group = _remove_suffix(group, '-1proc')
            test['treeherder-symbol'] = join_symbol(group, symbol)

            job['label'] = job['label'].replace('-1proc', '')
            job['name'] = _remove_suffix(job['name'], '-1proc')
            job['treeherder']['symbol'] = test['treeherder-symbol']
        else:  # e10s in the future
            test['test-name'] = add_suffix(test['test-name'], '-e10s')
            test['try-name'] = add_suffix(test['try-name'], '-e10s')
            group, symbol = split_symbol(test['treeherder-symbol'])
            if group != '?':
                group = add_suffix(group, '-e10s')
            test['treeherder-symbol'] = join_symbol(group, symbol)

            job['label'] += '-e10s'
            job['name'] = add_suffix(job['name'], '-e10s')
            job['treeherder']['symbol'] = test['treeherder-symbol']

test['try-name'] = _remove_suffix(test['try-name'], '-1proc')
            group, symbol = split_symbol(test['treeherder-symbol'])
            if group != '?':
                group = _remove_suffix(group, '-1proc')
            test['treeherder-symbol'] = join_symbol(group, symbol)

            job['label'] = job['label'].replace('-1proc', '')
            job['name'] = _remove_suffix(job['name'], '-1proc')
            job['treeherder']['symbol'] = test['treeherder-symbol']
        else:  # e10s in the future
            test['test-name'] = add_suffix(test['test-name'], '-e10s')
            test['try-name'] = add_suffix(test['try-name'], '-e10s')
            group, symbol = split_symbol(test['treeherder-symbol'])
            if group != '?':
                group = add_suffix(group, '-e10s')
            test['treeherder-symbol'] = join_symbol(group, symbol)

            job['label'] += '-e10s'
            job['name'] = add_suffix(job['name'], '-e10s')
            job['treeherder']['symbol'] = test['treeherder-symbol']

        yield job

def build_treeherder_definition(config, tasks):
    for task in tasks:
        dep = task.pop("primary-dependency")

        task.setdefault("treeherder", {}).update(inherit_treeherder_from_dep(task, dep))
        job_group = dep.task["extra"]["treeherder"].get("groupSymbol", "?")
        job_symbol = task["treeherder"].pop("job-symbol")
        full_symbol = join_symbol(job_group, job_symbol)
        task["treeherder"]["symbol"] = full_symbol

        yield task