Remove extraneous OTM codes and their species duplicates

We want to add a uniqueness constraint on `Species` objects:
    `(instance, common_name, genus, species, cultivar, other_part_of_name)` should be unique.

But we have duplicates in our own data -- 6 cases where two OTM codes have the same species info.
For those 6 pairs we'll keep one and kill the other, updating uses in our i-Tree code tables.
Luckily, no production instance has a tree or i-Tree code override pointing to one of the species we want to kill.

Here are the pairs, with lines showing (otm_code -> itree_code in itree_region).
* indicates variants to delete.

Yellow buckeye (Aesculus octandra)
    AEFL -> BDL OTHER in PiedmtCLT
   *AEOC -> AEHI in NoEastXXX

Paraguay nightshade (Lycianthes rantonnei)
   *LYRA -> BES OTHER in CaNCCoJBK
    SO1  -> BES OTHER in SoCalCSMA

Tipu tree (Tipuana tipu)
   *TITI2 -> BDL OTHER in CenFlaXXX
    TITU  -> BDL OTHER in TropicPacXXX

Oriental arbor vitae (Platycladus orientalis)
    PLOR80 -> CEL OTHER in TropicPacXXX
   *THOR   -> THOR in CenFlaXXX
              CES OTHER in InlEmpCLM
              CES OTHER in SoCalCSMA
              BES OTHER in SWDsrtGDL

Winter cassia (Cassia bicapsularis)
   *CABI2 -> BDS OTHER in CenFlaXXX
    SEBI5 -> BDS OTHER in GulfCoCHS

Patmore ash (Fraxinus pennsylvanica, "Patmore")
   *FRPE2  -> FRPE in InterWABQ
    FRPE_P -> FRPE_M in InlValMOD