Remove autosummary for available plugins list

This commit removes the autosummary directives for building the
documentation for the plugin classes. In the interest of time and
combining it with the existing aqc docs we'll do this in a follow up
for 1.0.0 after 1.0.0rc1 has been tagged.

qiskit/transpiler/passes/synthesis/plugin.py

@@ -336,63 +336,6 @@ def run(self, high_level_object, coupling_map=None, target=None, qubits=None, **
    HighLevelSynthesisPlugin
    HighLevelSynthesisPluginManager
    high_level_synthesis_plugin_names
-
-Available Plugins
-=================
-
-The below are the plugin classes which includes documentation on the various
-methods that are implemented by each plugin and the corresponding plugin name
-to use the method (this is not the class name). These classes should not be
-used directly, but instead should be used through the plugin interface documented
-above. The classes are listed here to find the documentation for each of the included
-plugins.
-
-Unitary Synthesis Plugins
--------------------------
-
-.. autosummary::
-   :toctree: ../stubs/
-
-   ~qiskit.transpiler.passes.synthesis.unitary_synthesis.DefaultUnitarySynthesis
-   ~qiskit.transpiler.passes.synthesis.aqc_plugin.AGSynthesisClifford
-   ~qiskit.transpiler.passes.synthesis.aqc_plugin.ACGSynthesisPermutation
-   ~qiskit.transpiler.passes.synthesis.solovay_kitaev_synthesis.SolovayKitaevSynthesis
-
-
-High Level Synthesis
---------------------
-
-Clifford Synthesis
-''''''''''''''''''
-
-.. autosummary::
-   :toctree: ../stubs/
-
-   ~qiskit.transpiler.passes.synthesis.high_level_synthesis.DefaultSynthesisClifford
-   ~qiskit.transpiler.passes.synthesis.high_level_synthesis.BMSynthesisClifford
-   ~qiskit.transpiler.passes.synthesis.high_level_synthesis.GreedySynthesisClifford
-   ~qiskit.transpiler.passes.synthesis.high_level_synthesis.LayerSynthesisClifford
-   ~qiskit.transpiler.passes.synthesis.high_level_synthesis.LayerLnnSynthesisClifford
-
-Linear Function Synthesis
-'''''''''''''''''''''''''
-
-.. autosummary::
-   :toctree: ../stubs/
-
-   ~qiskit.transpiler.passes.synthesis.high_level_synthesis.DefaultSynthesisLinearFunction
-   ~qiskit.transpiler.passes.synthesis.high_level_synthesis.KMSSynthesisLinearFunction
-   ~qiskit.transpiler.passes.synthesis.high_level_synthesis.PMHSynthesisLinearFunction
-
-Permutation Synthesis
-'''''''''''''''''''''
-
-.. autosummary::
-   :toctree: ../stubs/
-
-   ~qiskit.transpiler.passes.synthesis.high_level_synthesis.KMSSynthesisPermutation
-   ~qiskit.transpiler.passes.synthesis.high_level_synthesis.BasicSynthesisPermutation
-   ~qiskit.transpiler.passes.synthesis.high_level_synthesis.TokenSwapperSynthesisPermutation
 """
 
 import abc