Fix non-SSP2-NPi2025 scenarios to SSP2-NPi2025 until 2025.

[laurinks]

Purpose of this PR

Following the logic that all SSP scenarios (Pop, GDP, energy demand) should be equal in 2025 and only differ thereafter (see issue 361), this PR implements the following changes:

1. For all SSPx-NPi2025 scenarios with x = 1,3,5,2_lowEn, the start year is set to 2030 and the fixing until 2025 (path_gdx_ref) is set to SSP2-NPi2025.
2. NPi2025 is used as reference for computing policy costs by setting path_gdx_refpolicycost to SSPx-NPi2025.
3. For all NDC scenarios, path_gdx_bau is set to SSP2-NPi (resp. SSP2-EU21-NPi). This is a convenient choice as it means that no SSPx-NPi runs except for x=2,2-EU21, and not SSPx-Base runs are needed. Note that we will need to revisit this choice in the process of reworking the NDC scenario as pointed out here by @RahelMA.

To consolidate the number of default scenarios, we only run the "old" NPi scenario for SSP2 and SSP2-EU21 (although calibration for all SSPs continues to be based on the "old" NPi). Moreover, we only run the "old" NDCsy2025 (i.e. with start year 2025) scenario for SSP2 and SSP2-EU21. This results in 8 SSP2 scenarios, 7 SSP2-EU21 scenario, and 4 SSPx scenarios for each x = 1,3,5,2_lowEn, i.e. 31 in total instead of previously 39.

Type of change

• [x] Minor change (default scenarios show only small differences)

Checklist:

• [ ] My code follows the coding etiquette
• [x] I performed a self-review of my own code
• [x] I explained my changes within the PR, particularly in hard-to-understand areas
• [ ] I checked that the in-code documentation is up-to-date
• [ ] I adjusted the reporting in remind2 where it was needed
• [ ] I adjusted forbiddenColumnNames in readCheckScenarioConfig.R in case the PR leads to deprecated switches
• [x] All automated model tests pass (FAIL 0 in the output of make test)
• [ ] The changelog CHANGELOG.md has been updated correctly

Further information (optional):

• Test runs are here:
• You can find an SSP1-NPi2025 run with start year 2030 (fixing to SSP2-NPi2025) here: /p/projects/piam/scenariomip/main_v4/remind/output/C_SMIPv04-M-SSP1-NPi2025-var-rem-1
• You can find an SSP1-NPi run with start year 2025 (fixing to SSP2-NPi) here: /p/projects/piam/scenariomip/main_v4/remind/output/C_SMIPv04-M-SSP1-NPi2020-var-rem-1