Consolidate and simplify MTD modifiers

[kpedro88]

PR description:

Addresses part of #27450:

• merge the modifiers phase2_timing_layer and phase2_timing_layer_bar
• remove the modifier phase2_timing_layer_tile
• simplify the naming of Phase2 top-level Eras (since only Eras appended with "_timing_layer_bar" are used)

No changes in C++ code are made here; those are left to the MTD expert developers.

Additionally, the changes are propagated to the various test configs scattered throughout CMSSW. Normally I do not guarantee support for such configs, but in this case it was a one-line command to update them.

PR validation:

Ran workflow 20434.0 successfully.

[kpedro88]

please test

[ianna]

+1

[chayanit]

+1

[jfernan2]

+1

[kpedro88]

+upgrade

[slava77]

+1

for #28387 b6e659a

• changes are essentially technical for reco configs (consolidation of phase2_timing_layer and phase2_timing_layer_bar modifiers into one)
• jenkins tests pass and comparisons with the baseline show no differences

[civanch]

+1

[fabiocos]

+operations

the update of central configurations is coherent with the target of the this PR

[fabiocos]

+1

@rekovic the update in L1T configuration looks straightforward

[fabiocos]

merge