execution: use regular map in binary expressions

[MichaHoffmann]

The author of the umap package was also coauthor of the new go1.24 maps. There is no major regression here and it gets rid of a dependency:

$ go tool -modfile go.tools.mod benchstat benchmarks/main.out  benchmarks/pr.out 
goos: linux
goarch: amd64
pkg: github.com/thanos-io/promql-engine/engine
cpu: 13th Gen Intel(R) Core(TM) i7-13800H
                                                      │ benchmarks/main.out │         benchmarks/pr.out          │
                                                      │       sec/op        │    sec/op     vs base              │
RangeQuery/binary_operation_with_one_to_one-20                 47.69m ± ∞ ¹   51.27m ± ∞ ¹  +7.49% (p=0.008 n=5)
RangeQuery/binary_operation_with_many_to_one-20                114.3m ± ∞ ¹   121.9m ± ∞ ¹       ~ (p=0.095 n=5)
RangeQuery/binary_operation_with_vector_and_scalar-20          91.39m ± ∞ ¹   93.33m ± ∞ ¹       ~ (p=0.421 n=5)
geomean                                                        79.27m         83.56m        +5.41%
¹ need >= 6 samples for confidence interval at level 0.95

                                                      │ benchmarks/main.out │          benchmarks/pr.out          │
                                                      │        B/op         │     B/op       vs base              │
RangeQuery/binary_operation_with_one_to_one-20                13.53Mi ± ∞ ¹   13.58Mi ± ∞ ¹       ~ (p=0.310 n=5)
RangeQuery/binary_operation_with_many_to_one-20               33.58Mi ± ∞ ¹   33.60Mi ± ∞ ¹       ~ (p=0.841 n=5)
RangeQuery/binary_operation_with_vector_and_scalar-20         29.65Mi ± ∞ ¹   29.69Mi ± ∞ ¹       ~ (p=0.421 n=5)
geomean                                                       23.80Mi         23.84Mi        +0.17%
¹ need >= 6 samples for confidence interval at level 0.95

                                                      │ benchmarks/main.out │         benchmarks/pr.out          │
                                                      │      allocs/op      │  allocs/op    vs base              │
RangeQuery/binary_operation_with_one_to_one-20                 47.25k ± ∞ ¹   47.34k ± ∞ ¹       ~ (p=0.151 n=5)
RangeQuery/binary_operation_with_many_to_one-20                81.78k ± ∞ ¹   81.78k ± ∞ ¹       ~ (p=0.730 n=5)
RangeQuery/binary_operation_with_vector_and_scalar-20          62.59k ± ∞ ¹   62.60k ± ∞ ¹       ~ (p=0.794 n=5)
geomean                                                        62.31k         62.35k        +0.06%
¹ need >= 6 samples for confidence interval at level 0.95

I also made "benchstat" a tool in the go.tools.mod modfile

[saswatamcode]

Thanks!