Update descriptive metadata mapping to not attempt to structure table of contents note

[arcadiafalcone]

Currently the MODS>Cocina mapping parses the separator -- to map a MODS tableOfContents to a cocina note.structuredValue. This process is causing a blank value validation error when the MODS table of contents includes a double separator (-- --). This enhanced parsing is not necessary and should be removed to prevent these errors. Instead of separating the table of contents by -- into a structuredValue, the value as it appears in MODS should map to value.

This is preventing the records from being refreshed to fix the value/parallelValue validation error in sul-dlss/argo#4279.

Corresponding rspec test:

cocina-models/spec/cocina/models/mapping/descriptive/mods/table_of_contents_spec.rb

Line 28 in b642e33

it_behaves_like 'MODS cocina mapping' do

Honeybadger error: https://app.honeybadger.io/projects/50568/faults/104757394/01HRD1D0KSS2GB9G3J6XGP52K5?page=0#notice-trace

Example from: yz568jt0899
MODS
<tableOfContents displayLabel="Incomplete contents">ḥeleḳ 1. Be-reshit -- -- ḥeleḳ 3. Ṿa-yiḳra -- ḥeleḳ 4. Ba-midbar</tableOfContents>
Cocina
{ note: [ { value: `ḥeleḳ 1. Be-reshit -- -- ḥeleḳ 3. Ṿa-yiḳra -- ḥeleḳ 4. Ba-midbar`, type: 'table of contents', displayLabel: 'Incomplete contents' } ] }

Other examples: pm606ht7447, pg731bz2048

[mjgiarlo]

This should go out to production with weekly updates on Monday.